bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA demethylase FTO participates in malignant progression of gastric cancer by regulating SP1-AURKB-ATM pathway
Authors: Zeng Xueliang , Lu Yao , Zeng Taohui , Liu Wenyu , Huang Weicai , Yu Tingting , Tang Xuerui , Huang Panpan , Li Bei , Wei Hulai
Published: July 2024

Gastric cancer (GC) is the 5th most prevalent cancer and the 4th primary cancer-associated mortality globally. As the first identified m6A demethylase for removing RNA methylation modification, fat mass and obesity-associated protein (FTO) plays instrumental roles in cancer development. Therefore, we study the biological functions and oncogenic mechanisms of FTO in GC tumorigenesis and progression. In our study, FTO expression is obviously upregulated in GC tissues and cells. The upregulation of FTO is associated with advanced nerve invasion, tumor size, and LNM, as well as the poor prognosis in GC patients, and promoted GC cell viability, colony formation, migration and invasion. Mechanistically, FTO targeted specificity protein 1 and Aurora Kinase B, resulting in the phosphorylation of ataxia telangiectasia mutated and P38 and dephosphorylation of P53. In conclusion, the m6A demethylase FTO promotes GC tumorigenesis and progression by regulating the SP1-AURKB-ATM pathway, which may highlight the potential of FTO as a diagnostic biomarker for GC patients’ therapy response and prognosis.
Titanic lessons for Spaceship Earth to account for human behavior in institutional design
Authors: Lindahl Therese , Anderies John M. , Crépin Anne-Sophie , Jónás Krisztina , Schill Caroline , Cárdenas Juan Camilo , Folke Carl , Hofstede Gert Jan , Janssen Marco A. , Mathias Jean-Denis , Polasky Stephen
Published: July 2024

Combating environmental degradation requires global cooperation. We here argue that institutional designs for such efforts need to account for human behavior. The voyage of the Titanic serves as an analogous case to learn from, and we use behavioral insights to identify critical aspects of human behavior that serve as barriers or opportunities for addressing the challenges we face. We identify a set of public goods that may help us mitigate identified negative aspects of human behavior, while leveraging the positive aspects: standards and best practices, mechanisms for large-scale coordination, and curation of information to raise awareness and promote action. We use existing international organizations, providing at least one of these capacities, as cases to learn from before applying our insights to existing institutional solutions for global environmental protection. We identify institutional design features that, if adapted to better account for human behavior, could lead to more effective institutional solutions.
Antiferromagnetic spintronics and beyond
Authors: Dal Din A. , Amin O. J. , Wadley P. , Edmonds K. W.
Published: July 2024

In this review article, we summarize some recent key results in the development of antiferromagnetic spintronics. Current-induced switching of the Néel vector orientation has now been established in a wide range of antiferromagnetic films and antiferromagnet / heavy metal bilayers, as well as current-driven motion of antiferromagnetic spin textures. The latter are particularly promising due to their small size and topological stability, but reading their magnetic state presents challenges. We also focus on materials whose compensated spin arrangements (either collinear or noncollinear) are coexistent with a spin-split band structure, enabling first-order spintronic phenomena including giant and tunneling magnetoresistance, and the anomalous Hall effect. The resulting combination of efficient electrical readout mechanisms with the advantages of a near-zero net magnetization has potential to be transformative for spintronic applications.
Observation of the liquid metal phase transition in optofluidic microcavities
Authors: Fu Zixiang , Zhao Zhenlin , Dong Ruiji , Guo Junqiang , Zhang Yan-Lei , Xie Shusen , Zhang Xianzeng , Lu Qijing
Published: July 2024

Gallium (Ga) exhibits remarkable potential in flexible electronics, chemistry, and biomedicine due to its exceptional physical properties. The phase transition and supercooling characteristics of Ga have led to the emergence of numerous valuable applications. In this paper, we capitalize on this foundation by utilizing optofluidic microcavities supporting both high quality factor optical and optomechanical modes to investigate the phase transformation process and supercooling properties of Ga. Our study provides comprehensive insights into the dynamic behavior of Ga during the complete phase transition, such as measuring a hysteresis loop between the solid-to-liquid and liquid-to-solid transitions, revealing nonreciprocal resonance wavelength shift, and identifying a unique metastability state of Ga during melting. The linear thermal expansion coefficients of Ga were precisely measured to be 0.41 × 10−5 K−1 and −0.75 × 10−5 K−1 for solid and liquid Ga, respectively. Our research provides a comprehensive and versatile monitoring platform for newly fabricated liquid metal alloys, offering multidimensional insights into their phase transition behavior.
Cavity-enhanced narrowband spectral filters using rare-earth ions doped in thin-film lithium niobate
Authors: Zhao Yuqi , Renaud Dylan , Farfurnik Demitry , Jiang Yuxi , Dutta Subhojit , Sinclair Neil , Lončar Marko , Waks Edo
Published: July 2024

On-chip optical filters are fundamental components in optical signal processing. While rare-earth ion-doped crystals offer ultra-narrow optical filtering via spectral hole burning, their applications have primarily been limited to those using bulk crystals, restricting their utility. In this work, we demonstrate cavity-enhanced spectral filtering based on rare-earth ions in an integrated nonlinear optical platform. We incorporate rare-earth ions into high quality-factor ring resonators patterned in thin-film lithium niobate. By spectral hole burning at 4 K in a critically coupled resonance mode, we achieve bandpass filters ranging from 7 MHz linewidth, with 13.0 dB of extinction, to 24 MHz linewidth, with 20.4 dB of extinction. By reducing the temperature to 100 mK to eliminate phonon broadening, we achieve an even narrower linewidth of 681 kHz, which is comparable to the narrowest filter linewidth demonstrated in an integrated photonic device, while only requiring a small device footprint. Moreover, the cavity enables reconfigurable filtering by varying the cavity coupling rate. For instance, as opposed to the bandpass filter, we demonstrate a bandstop filter utilizing an under-coupled ring resonator. Such versatile integrated spectral filters with high extinction ratio and narrow linewidth could serve as fundamental components for optical signal processing and optical memories on-a-chip.
Critical Materials for a Low-carbon Economy
Authors: Segal David
Published: July 2024

Countries worldwide are moving to a future without fossil fuels to mitigate the effects of climate change. This transition will involve phasing out the fossil fuels used for electricity generation, the liquid fuels used for transportation and the gas that is used to heat homes. To achieve the transition, a range of materials, known as critical materials or critical minerals are essential. These range from the lithium needed for batteries to store power to the neodymium needed for the magnets that convert motion to electricity in wind turbines.

Critical Materials for a Low-carbon Economy looks at the science behind some of the materials that will be essential to this transition. Beginning with an introduction to the origins of climate change and the importance of critical materials this book is split into chapters focusing on different technologies. In addition to describing the science behind the need for these materials it also discusses issues around supply chains and geopolitical considerations.
Application of biomaterials in the treatment of intracerebral hemorrhage
Authors: Wang Wei , Liu Xiaowen , Wang Yupeng , Zhou Dongfang , Chen Lukui
Published: July 2024

In this review, the application of nanomaterials and hydrogels in the treatment of intracerebral hemorrhage is summarized. In addition, the potential challenges and prospects of these biomaterials for clinical translation are discussed.
Polyaniline (PANI) nanocomposites with Se, Te and their metal chalcogenides: a review
Authors: Yadav Alok Kumar , Mohammad Naeem , Chamanehpour Elham , Mishra Yogendra Kumar , Khanna Pawan K.
Published: July 2024

This review presents a through literature survey covering methods of synthesis of Se/Te chalcogen- and their chalcogenide-based polyaniline nanocomposites and their properties and potential application.
Heterogeneous density-based clustering with a dual-functional memristive array
Authors: Shin Dong Hoon , Cheong Sunwoo , Lee Soo Hyung , Jang Yoon Ho , Park Taegyun , Han Janguk , Shim Sung Keun , Kim Yeong Rok , Han Joon-Kyu , Baek In Kyung , Ghenzi Néstor , Hwang Cheol Seong
Published: July 2024

A reconfigurable dual-mode memristive array was utilized for the proposed heterogeneous density-based clustering. Both digital and analog modes were analyzed, and the algorithm was verified through vector–matrix multiplication in both modes.
Nickel coating on plasmonic copper nanoparticles lowers cytotoxicity and enables colorimetric pH readout for antibacterial wound dressing application
Authors: Zhang Bohan , Slavkovic Sladjana , Qiu Yumin , Peng Chun , Chen Jennifer I-Ling
Published: July 2024

Nickel coating on plasmonic copper nanoparticles enhances chemical stability, reduces cytotoxicity while providing antibacterial activity and colorimetric response to pH.
Effect of leucine as an aerosolization enhancer on the bioactivity of spray dried viral-vectored vaccines for inhalation
Authors: Singh Varsha , Dolovich Myrna , Xing Zhou , Cranston Emily D. , Thompson Michael R.
Published: July 2024

We explore the advantages and disadvantages of l-leucine on spray dried vaccine formulations.
Recent advances on carbon nitride-based photocatalysts for organic transformations in aqueous media
Authors: Zhou Pengfei , Cai Yunfei , Tang Yurong
Published: July 2024

This review highlights recent advancements in photocatalytic organic transformations in aqueous media employing the water-compatible solid-state sensitizer carbon nitride and its derivatives as catalysts.
Detour to success: photoswitching via indirect excitation
Authors: Kuntze Kim , Isokuortti Jussi , van der Wal Jacob J. , Laaksonen Timo , Crespi Stefano , Durandin Nikita A. , Priimagi Arri
Published: July 2024

Photoswitching via indirect excitation allows harnessing low-energy photons to control molecular configuration. Herein, the state of the art of the predominant indirect photoswitching methods is presented.
2D anti-MXene boride monolayers: unveiling a promising new family of catalysts for the nitrogen reduction reaction
Authors: Bui Viet Q. , Khieu Dinh Quang
Published: July 2024

Through a comprehensive DFT study, this work investigates the dynamic, mechanical, and thermal stabilities of anti-MXene borides, highlighting FeB and OsB as highly efficient NRR electrocatalysts with low overpotentials and superior selectivity.
Essence of electrochemical prelithiation of the silicon anode: from the interface to the bulk phase
Authors: Li Yuchen , Lv Linze , Liang Rui , Wang Longfei , Wang Yan , Qu Qunting , Shen Ming , Zheng Honghe
Published: July 2024

The previous understanding of prelithiation is still limited to the stage of compensating the lithium loss. Herein, the further essence of electrochemical prelithiation in regulating the SEI film and stabilizing the Lix–Si phase is put forward.
Defective Cr2CTx-based sensors with high sensitivity for NO2 detection at room temperature
Authors: Guo Liangchao , Han Haoran , Wang Junke , Wang Peng , Du Chunyu , Wang Bo , Yuan Qilong , Zhai Yongbiao , Zhang Chao
Published: July 2024

A Cr2CTx-based gas sensor exhibited high selectivity for NO2 at room temperature. DFT unveiled the adsorption capacity of different gases consistent with experimental results.
Flexible and transparent nanohole-patterned films with antibacterial properties against Staphylococcus aureus
Authors: Kim Hee-Kyeong , Park Jeong-Hun , Jang Min-Jun , Han Su-Ji , Cho Young-Sam , Park Hyun-Ha
Published: July 2024

In this study, the multi-functional nanohole array film was developed for antibacterial activity against Staphylococcus aureus (S. aureus), a common opportunistic pathogen.
NIR II-responsive core–shell La2O2S:Er3+@La2O2S nanoparticles towards 1.5 μm photodetection
Authors: Dong Xinyao , Zhou Na , Tian Minfeng , Ji Yanan , Wang Jingxuan , Fan Jianing , Li Heyang , Xu Wen , Duan Ping , Yin Xiumei
Published: July 2024

Schematic diagram of a 1550 nm near-infrared photoelectric detector based on a MAPbI3/La2O2S:2%Er3+@La2O2S structure.
Dry ionic conductive elastomers based on polymeric deep eutectic solvents for bioelectronics
Authors: Picchio Matías L. , Dominguez-Alfaro Antonio , Minari Roque J. , Mota-Morales Josué D. , Mecerreyes David
Published: July 2024

This review highlights the recent progress on polymerizable deep eutectic solvents (PDES) and polyDES as liquid-free ionic elastomers in bioelectronics and discusses future directions on how these functional polymers can expand the field.
Fabrication of low thermal expansion coefficient electrodeposited Invar alloy films by hydrogen annealing for OLED fine metal masks
Authors: Ren Wei , Lan Xi , Guo Lei , Guo Zhancheng
Published: July 2024

This study unveils the dependence of the Invar effect on grain size. An electrodeposited Invar alloy film was prepared with near-zero inclusions and near-zero thermal expansion, which will advance its application in OLED fine metal masks.
Robust DOA estimation for two‐level nested arrays in unknown mutual coupling
Authors: He Shun , Li Xue , Sun Bing
Published: July 2024

Aiming at solving the problem that the capability of direction of arrival method for estimation of nested arrays decreases sharply under unknown mutual coupling, an iterative weighted low‐rank matrix reconstruction algorithm is proposed here. First, the received data covariance matrix is extended, and a weighted low‐rank matrix recovery problem is formulated for joint estimations of the Toeplitz matrix and mutual coupling coefficients. Next, the direction of arrival from recovered Toeplitz matrix is retrieved by using the root multiple signal classification algorithm. Simulation results show that iterative weighted low‐rank matrix reconstruction algorithm can effectively avoid the influence of mutual coupling while solving the grid‐mismatch problem so that the accuracy and the resolution of estimation are improved.
Feeding‐line‐based decoupling patch antennas
Authors: Gu Hui , Qi Hang , Zhao Yue , Ge Lei , Zhang Wenjing
Published: July 2024

Mutual coupling among multiple antennas has been a problem needed to be tackled in multiple‐input‐multiple‐output (MIMO) systems. A decoupling method based on short decoupling feeding lines (DFLs) for MIMO patch antennas is proposed. The decoupling method utilises the feeding transmission line to create a new coupling path between the closely placed patch antennas. By adjusting the intensity and phase of the introduced new coupling, the original coupling can be cancelled out. The proposed method can realise both E‐ and H‐plane decoupling. A 1 × 2 H‐plane MIMO patch antenna array is first presented to explain the decoupling mechanism. Then, two practical examples of 2 × 2 and 4 × 4 MIMO patch antenna arrays are designed, fabricated and measured. The results indicate that the port isolation can be apparently improved from 15 to 38 dB for H‐plane coupling and from 19 to 35 dB for E‐plane coupling at the centre frequency of 3.5 GHz. Moreover, the proposed method is promising to be applied in arrays with other antenna type by adjusting the position and size of short DFLs.
Advancing smart tourism destinations: A case study using bidirectional encoder representations from transformers‐based occupancy predictions in torrevieja (Spain)
Authors: Giménez Manuel José Ginés , Giner Pérez de Lucia José , Celdrán Bernabeu Marco Antonio , Mazón López José Norberto , Cano Escribá Juan Carlos , Cecilia Canales José María
Published: July 2024

Tourism represents a crucial socio‐economic pillar globally, yet the multifaceted challenges it poses necessitate innovative management approaches. The paradigm of smart tourism harnesses advanced data analytics tools to promote both profitability and sustainability in tourist destinations, leading to new levels of destination smartness. Accurate tourist occupancy prediction, particularly in areas dominated by second‐home accommodations where traditional hospitality data may be insufficient, plays a key role in optimising tourism management. To address this data gap, our prior research employed ARIMA modelling on Airbnb booking time series and analysed tourism‐related Twitter conversations to forecast occupancy levels in Torrevieja (Alicante); a prominent second‐home tourism destination in Southeastern Spain. In this extended study, we delve deeper into the realm of social sensing by utilising bidirectional encoder representations from transformers (BERT) for topic modelling. Our methodology involves the processing and analysis of Twitter data to identify prominent themes related to Torrevieja. The findings not only reveal nuanced perceptions and discussions about the destination but also underscore the effectiveness of BERT in capturing intricate topic dynamics. Importantly, this work highlights how the alignment of specific topics with booking patterns can further enhance predictive accuracy for tourist occupancy, presenting a robust toolkit for stakeholders in the tourism sector.
A novel ensemble deep reinforcement learning model for short‐term load forecasting based on Q‐learning dynamic model selection
Authors: He Xin , Zhao Wenlu , Zhang Licheng , Zhang Qiushi , Li Xinyu
Published: July 2024

Short‐term load forecasting is critical for power system planning and operations, and ensemble forecasting methods for electricity loads have been shown to be effective in obtaining accurate forecasts. However, the weights in ensemble prediction models are usually preset based on the overall performance after training, which prevents the model from adapting in the face of different scenarios, limiting the improvement of prediction performance. In order to improve the accurateness and validity of the ensemble prediction method further, this paper proposes an ensemble deep reinforcement learning approach using Q‐learning dynamic weight assignment to consider local behaviours caused by changes in the external environment. Firstly, the variational mode decomposition is used to reduce the non‐stationarity of the original data by decomposing the load sequence. Then, the recurrent neural network (RNN), long short‐term memory (LSTM), and gated recurrent unit (GRU) are selected as the basic power load predictors. Finally, the optimal weights are ensembled for the three sub‐predictors by the optimal weights generated using the Q‐learning algorithm, and the final results are obtained by combining their respective predictions. The results show that the forecasting capability of the proposed method outperforms all sub‐models and several baseline ensemble forecasting methods.
White dwarf magnetospheres: Shielding volatile content of icy objects and implications for volatile pollution scarcity
Authors: Zhou Wen-Han , Liu Shang-Fei , Lin Douglas N. C.
Published: July 2024

Context. About 25–50% of white dwarfs are found to be contaminated by heavy elements, which are believed to originate from external sources such as planetary materials. Elemental abundances suggest that most of the pollutants are rocky objects and only a small fraction of white dwarfs bear traces of volatile accretion.

Aims. In order to account for the scarcity of volatile pollution, we investigate the role of the white dwarfs’ magnetospheres in shielding the volatile content of icy objects.

Methods. We estimated the volatile sublimation of inward drifting exocomets. We assume the orbits of the exocomets are circularized by the Alfvén wing drag that is effective for long-period comets.

Results. Volatile material can sublimate outside the corotation radius and be shielded by the magnetic field. The two conditions for this volatile-shielded mechanism are that the magnetosphere radius must be larger than the corotation radius and that the volatiles are depleted outside the corotation radius, which requires a sufficiently slow orbital circularization process. We applied our model to nine white dwarfs with known rotational periods, magnetic fields, and atmosphere compositions. Our volatile-shielded model may explain the excess of volatile elements such as C and S in the disk relative to the white dwarf atmosphere in WD2326+049 (G29-38). Nevertheless, given the sensitivity of our model to the circularization process and material properties of icy objects, there remains considerable uncertainty in our results.

Conclusions. We emphasize the importance of white dwarfs’ magnetic fields in preventing the accretion of volatile gas onto them. Our work suggests a possible explanation for the scarcity of volatile-accretion signatures among white dwarfs. We also identify a correlation between the magnetic field strength, the spin period, and the composition of pollutants in white dwarf atmospheres. However, given the uncertainties in our model, more observations are necessary to establish more precise constraints on the relevant parameters.
Fundamental study on the effect of grain size distribution on angle of repose
Authors: Kajiyama Shintaro , Nakata Yukio , Nakase Hitoshi
Published: July 2024

In this study, the authors developed a new sidewall velocity-controlled cylindrical angle of repose measurement apparatus that can capture images of a sand heap continuously using two orthogonal cameras in order to reduce the cost of photography. The developed apparatus was used to measure the angle from formation to repose of sand heap using different grain sizes distribution and to assess the effect of grain size distribution on the angle of repose. The formation process of the sand heap was continuously measured using the experimental apparatus, and it was found that the sand heap became steady state when it reached a certain height. It is inferred that the angle of repose measured in a stationary state indicates the inclination angle of the sand heap at a certain point in time, suggesting the possibility of obtaining a highly accurate angle of repose with fewer experiments by using this experimental apparatus to continuously acquire and average the inclination angle of a sand heap in a steady state. For samples with a stepped grain size distribution, the angle of repose was found to be higher than for samples with a gentle grain size distribution at the same 20% grain size D20 and mean grain size D50. It was found that the angle of repose increased logarithmically with increasing coefficient of uniformity. Based on these results, it is clear that for a well-graded sand, it is the grain size rather than the coefficient of uniformity that has an effect on the angle of repose.
Characterization of soil stiffness anisotropy at small strains based on phase velocities of shear waves measured by novel testing apparatus
Authors: Liu Junming , Otsubo Masahide , Kuwano Reiko
Published: July 2024

For the characterization of soil stiffness anisotropy at small strains and the calculation of soil elastic constants derived from the cross-anisotropic model, it is important to obtain stress wave phase velocities of soils in both principal and oblique directions. This study developed an original eight-prismatic shape apparatus equipped with disk-shaped shear plates to measure shear (S-) wave phase velocities (Vphase) in multiple directions, and four granular materials of various shapes were tested by this apparatus under isotropic confinement. Experimental results confirm the capability of the new apparatus and reveal that both S-wave propagation and oscillation directions are sensitive to soil inner fabric, i.e., Vs changes with the variation of either S-wave propagation or oscillation direction. Based on the experimental observations, it is suggested to keep the same S-wave oscillation direction when measuring Vs in multiple propagation directions so that the corresponding shape of the S-wave surface (polar plots of Vs in arbitrary propagation directions) is more precise to reflect the small-strain stiffness anisotropy of soils.
Effects of geometry of soil specimens on the formation of desiccation cracks
Authors: Seah Yew Heng Sherman , Leong Eng Choon
Published: July 2024

Desiccation cracks in soils are important in engineering structures that need hydraulic integrity such as earth dams, and containment facilities. At the element test level, such cracks are a hindrance when the volume change of the soil specimen needs to be measured during the test. One such test is the volumetric shrinkage test where the volume of the soil specimen needs to be continuously determined together with its mass change as the soil specimen dries. The soil specimen may deform non-uniformly. Previously hazardous and cumbersome methods using mercury or wax are needed to determine the volume of soil specimens that deform non-uniformly, but the advent of 3D scanning and photogrammetry enables the volume of non-uniform soil specimens to be measured quite accurately. However, such techniques cannot accurately determine the volume of the deformed soil specimen once cracks start appearing in the soil specimen. Volumetric shrinkage tests are commonly conducted for cylindrical soil specimens. This paper investigates the geometry (shapes and dimensions) of soil specimens other than cylindrical on the formation of desiccation cracks. Bentonite is used as the test soil as it experiences large volume change on drying. The test results provide guidance for the geometry of a soil specimen to be used in the volumetric shrinkage test.
A fully automated unsaturated triaxial device for testing of soils under complicated hydromechanical stress paths
Authors: Haeri Seyed Mohsen , Soleymani Borujerdi Saman , Akbari Garakani Amir
Published: July 2024

A fully-automated unsaturated triaxial device is developed at the Advanced Soil Mechanic Laboratory of the Sharif University of Technology (SUT) to investigate the hydromechanical behavior of unsaturated soils under any complicated path. The main improvements of the developed device are (1) the ability to continuously measure accurately different stress/strain variables during long duration of unsaturated tests. This is of great importance in capturing the sudden deformations of the specimen, under wetting (2) providing a user-friendly controller software enabling the definition of any desired stress/strain variable and stress/strain paths under either stress-controlled or strain-controlled conditions. Finally, to evaluate the performance of the developed apparatus, two wetting tests were carried out to study the effect of initial shear stress on the hydromechanical behavior of unsaturated reconstituted specimens of Gorgan loess. In these wetting tests, the specimens were wetted under isotropic and anisotropic stress states by stepwise reduction of suction to approach to the saturated condition. The obtained results showed the excellent performance of the developed device to accurately follow the defined stress path along with the continuous measurement of stress/strain variables. The tested collapsible soil specimen that was wetted under the effect of initial shear stress exhibited a larger volume decrease accompanied by a larger degree of saturation compared to those of the specimen wetted under the isotropic stress state with the same initial mean net stress.
The interpretation of advanced triaxial tests for the assessment of small strain stiffness
Authors: Gasparre Apollonia , Coop Matthew R.
Published: July 2024

The measurement of small strain stiffness of soils is affected by the techniques and procedures used in advanced triaxial tests, including the connection between the internal load cell and the sample top platen, the resolution of the instrumentation, the ratio of shearing axial strain rate to preceding creep strain rate. The interpretation of the measured data needs to consider how these factors have affected the measured stress-strain response of a sample. This paper reviews the current practice for performing advanced triaxial tests and discusses the interpretation of data resulting from advanced triaxial tests aimed at measuring the true stiffness of soils. It is concluded that the interpretation of the small strain stiffness of stiff clays affects the shape of the stiffness curve at medium to large strain levels and it is therefore relevant for engineering problems. Suitable specifications as well as a detailed review of the results of the tests are required to ascertain the reliability of the measured stiffness.
Experimental evidences of bio-chemo-mechanical processes in contaminated sediments
Authors: Sollecito Francesca , Plötze Michael , Puzrin Alexander M. , Vitone Claudia , Cotecchia Federica
Published: July 2024

The research shows the results of a micro to macro testing programme carried out on contaminated marine sediments from a natural deposit to assess the effects of bio-chemo-mechanical coupled processes which may act in complex natural environments and affect the geotechnical properties of the clays. The research has been triggered by the emblematic case of the contaminated Mar Piccolo (MP) basin in Taranto (Southern Italy), where the high degree of pollution recorded in the clayey sediments at the sea bottom, has been found to worsen water quality and promote bioaccumulation of pollutants in several species. Several samples of sediments collected in the basin from the top layer exhibited peculiar geotechnical properties, in terms of plasticity and activity indexes, compressibility and hydraulic permeability. The results of the geotechnical testing were interpreted taking into account the XRD mineralogical results and the chemical composition of the soil matrix. Furthermore, thermogravimetry tests results were examined to explore the nature of the sediment skeleton and of its organic matter content, based on the main thermal reactions occurring within different temperature ranges. Lastly, scanning electron microscopy and mercury intrusion porosimetry were performed to assess the sediment pore size distribution as well as their content in microfossils and diatoms. The original multiscale analysis carried out on some selected sediment samples showed that the biogeochemical degradation of organic matter and the presence of microfossils and diatoms significantly affect the micro to macro behaviour of marine sediments.
Development of tools to investigate biocementation - microscale analysis for studying bacterial solutions
Authors: Pinto Mariana , Cardoso Rafaela
Published: July 2024

Biocementation consists on the use of microorganisms (bacteria) to promote the precipitation of calcium carbonate (biocement). When this technique is applied in soils or fractured rocks, the biocement which is precipitated can fill voids and discontinuities, being easy to apply, not very intrusive and requiring low energy consumption. There are several aspects that must be investigated when using living microorganisms for such purpose, mainly related with ensuring the environmental conditions for their survival and the maximization of production of biocement. The age of the bacteria and the increment of biocement production after increasing the number of inoculations were investigated in the work presented in this paper. A microfluidic device was developed to visualize the production of biocement after multiple injections of bacteria and feeding solution. These devices allow for an easy and straight forward visualization of small-scale physical, chemical and biological processes. The results of injection cycles in microfluidics channel were examined with imaging techniques. In parallel, experimental tests were carried out on samples of uniform sand soil, with the objective of evaluating the penetration resistance and the calcium carbonate content that was formed, according to the number of injections. There was also a verification of the electrical conductivity of the bacterial solutions in use, to guarantee its viability. As expected, the production of biocement increased after three injections of bacteria, which is consistent with the results found in both microfluidic devices and soil samples.
Using X-ray micro CT imaging data to obtain particle morphology and soil fabric parameters
Authors: Valverde Ana , Wijewickreme Dharma
Published: July 2024

In addition to the well-understood effects of void ratio and effective confining stress on the mechanical behavior of finegrained soils, past experimental research at the University of British Columbia (UBC), Vancouver, Canada, has revealed a considerable effect of particle fabric on the monotonic and cyclic shear behavior of silts. With this background, an experimental research program was undertaken to further investigate the particulate nature and arrangement of silts. The fabric of soils has been traditionally associated with the matrix void ratio, but can be directly associated with fabric parameters like the coordination number. Furthermore, grain morphology has a significant impact on these characteristics. Advancements in acquiring digital images and associated processing have made it possible to obtain individual soil particle parameters such as length, width, breath, thickness, volume, etc., along with information on spatial location and orientation of a given particle - thus providing the data needed to determine contact fabric and morphology of a soil matrix. In order to calculate these parameters and look for any potential correlations, commercially available, precalibrated, standard-size silica having particles within the size range from 40 μm to 60 μm, were imaged and analyzed. This study establishes an approach for extracting void and morphological information from tomographic images using image analysis techniques and algorithms developed in-house. Initial observations related to particle morphology and preliminary fabric scalar parameters are discussed. This work contributes to the accounting for fabric in understanding the macroscopic shear behavior of silts from the Fraser River Delta, British Columbia, Canada.
Comparison of simple stress-strain models in the moderate strain range for fine-grained soils: A review
Authors: Beesley Mair , Ibraim Erdin , Vardanega Paul J.
Published: July 2024

The prediction of stress-strain behaviour in soils is a problem that can be approached in different ways depending on the design scenario. In some cases, a multi-parameter constitutive model calibrated with non-routine soil tests may be appropriate, for example, where a model has been developed for the relevant soil at a building site subject to complex loading. However, simple characteristic parameters are desirable for examining the variability of soil behaviour especially at regional scales. This paper describes a method of assessing the suitability of simple models for simulating non-linear undrained soil stress-strain behaviour in the moderate strain range. The moderate strain range is defined by a soil strength mobilisation of 20% to 80%. Three simple stress-strain models are compared. A published database of reconstituted triaxial tests is used to evaluate the three models with selected statistical tools that quantify errors associated with the simple model approximation of the relationship between stress and strain. The paper discusses the value of computing the model error and the trade off to make between introducing a greater number of parameters (and tests) for model precision and limiting the complexity of the variability characterisation.
Effects of cyclic loading on soil-geogrid interaction characteristics
Authors: Ferreira Fernanda B. , Vieira Castorina S. , Lopes Maria de Lurdes , Ferreira Pedro G.
Published: July 2024

The benefits of geosynthetic-reinforced soil systems over conventional earth-retaining structures are now well established. These reinforced systems are often subjected not only to static loads, but also to seismic and/or traffic loads, in which case the effects of repeated loading on soil-geosynthetic interaction characteristics should be properly considered. This study investigates the behaviour of a geogrid typically used for soil reinforcement under cyclic pullout loading through load-controlled laboratory pullout tests. To examine the influence of cyclic loading amplitude, number of cycles and static pullout force acting on the geogrid at the onset of cyclic loading, distinct loading patterns are considered. A well-graded residual soil from granite is used as backfill material. A comparison between the cyclic and monotonic pullout response of the reinforcement is then established in order to identify any potential strength loss attributed to cyclic loading. The experimental results show that the ultimate pullout resistance of the geogrid embedded in medium dense residual soil from granite may be adversely affected by cyclic loading. The cumulative cyclic displacements of the reinforcement are more pronounced during the initial loading cycles, but tend to stabilize with the increasing number of cycles when the soil is densely compacted. In the presence of dense soil, the cyclic strains of the geogrid specimen are particularly significant at the front section and almost negligible towards the back end.
Preliminary findings on the experimental investigation of the small-strain behaviour of Pizzoli silty sand
Authors: Chiaradonna Anna , Monaco Paola
Published: July 2024

The dynamic properties of soils play a crucial role in solving many geotechnical problems with special attention to earthquake engineering. In particular, the small-strain soil behavior should be accurately reproduced in geotechnical modelling to allow quantifying of the earthquake-induced site response. If the determination of the small-strain shear modulus can be easily inferred from in-situ measurements of shear wave velocity, the small-strain damping ratio of soils is rarely obtained from in-situ tests and it is commonly defined through cyclic or dynamic laboratory tests. This paper describes preliminary findings obtained from a laboratory investigation performed to measure the small-strain dynamic properties of the silty sand deposit of the Pizzoli site (L’Aquila, Italy). Due to the remarkable seismic hazard of the considered area, demonstrated by several seismic events, such as recently the 2009 L’Aquila and the 2016-2017 Central Italy earthquakes, and in the past, the 2 February 1703 earthquake, a specific investigation program including boreholes, geophysical and geotechnical in-situ tests was carried out. Resonant column tests have been also performed at the Geotechnical Laboratory of the University of L’Aquila in both forced and free vibration modes. The interpretation of the results has been used to identify the small-strain shear modulus and damping ratio. The shear modulus as obtained from the laboratory has been compared with that obtained via the existing in-situ shear wave velocity measurements. In contrast, the damping ratio has been compared with the value estimated with a literature relationship proposed for soil deposits of Central Italy.
Influence of the coefficient of uniformity on bio-cemented sands: A microscale investigation
Authors: Reed Marlee , Montoya Brina M.
Published: July 2024

Microbially induced carbonate precipitation (MICP) is a bio-mediated ground improvement technique that can increase soil stiffness and produce cohesion within granular material. Most experimental investigations on MICP-treated soils are performed on idealized granular materials. Evaluating a narrow range of particle sizes dismisses the potential influence of soil fabric on MICP treatment efficiency. Therefore, little is known regarding the influence of soil fabric on the level of improvement achievable post-MICP treatment. We investigate the influence of the coefficient of uniformity (Cu) on the level of improvement that can be obtained from MICP treatment. This study couples unconfined compression testing with microscale observations obtained from x-ray computed tomography (CT) of two sand mixtures with different Cu values. A soil column and CT specimen of each sand mixture were prepared and received the same number of MICPinjections. The shear wave velocity (Vs) of the soil columns was monitored to evaluate the increase in soil stiffness over time. After MICP treatment, the bio-cemented columns were subjected to unconfined compressive strength testing. Results indicate that for a similar mass of carbonate, the soil with a larger Cu experienced a greater increase in Vs but a lower maximum unconfined compressive strength. Through CT imaging, the soil with a smaller Cu was observed to have a more uniform distribution of carbonate within the sand matrix whereas the soil with a larger Cu has more sporadic MICP trends. This study elucidates the influence of soil fabric on the level of improvement that can be achieved through MICP treatment and assesses the reliability of x-ray CT scanning of MICP-treated sands with moderate carbonate content.
Indirect verification of suction in cyclic UCS tests of a chemically stabilized soil
Authors: Martins Ligia A. , Correia AntYónio A.S. , Oliveira Paulo J. Venda , Lemos Luis J.L.
Published: July 2024

The present study aims to indirectly evaluate the occurrence of suction and its effects in laboratory tests of a chemically stabilized soft soil. To achieve these goals, a series of unconfined compressive strength (UCS) and triaxial tests were performed, with and without the application of cyclic loading and with and without membrane during the cyclic loading stage, to evaluate the occurrence of suction and its effect on the mechanical behavior of a chemically stabilized soft soil. The results show that during the cyclic loading stage there is an occurrence of suction which influences both the permanent axial strain during the cyclic loading and the maximum strength of the stabilized soil. During the cyclic loading stage, the occurrence of suction promoted the increase of the plastic deformation. In terms of strength, it is observed an occurrence of suction in the stabilized soil which may be related with the increase of the strength. It is observed that suction can be avoided by saturation of the sample, verified in triaxial tests, or by using a membrane during the cyclic UCS test.
Effect of fibre orientation on the mechanical response of reinforced sand, detected with x-ray tomography
Authors: Arciero Michela , Salvatore Erminio , Tengattini Alessandro , Modoni Giuseppe , Viggiani Gioacchino
Published: July 2024

The mechanical behaviour of fibre-reinforced sands (FRS) has been thoroughly explored with a laboratory study, firstly investigating the influence of relevant parameters such as grading index, soil density, amount, diameter, and length of fibres then focusing on their orientation with respect to the principal stress directions. This aspect has been deeply investigated performing parallel tests on samples of pure sand and on samples with randomly and uniformly oriented fibres compacted at a similarly high relative density (Dr≈1). Direct and triaxial shear tests have been performed, the former enforcing deformation on a predetermined shear plane. The results show that reinforcement with oriented fibres provides a higher strength and ductility to the sand. The grain scale investigation of the materials’ response to direct shearing has been carried out performing X-ray tomography post-mortem (i.e., after the test). The evolution of porosity in several samples prepared with the same procedure and sheared under the same conditions has been studied freezing the material fabric with nanosilica grout injected at different displacement levels. On the contrary, X-ray tomography performed along with miniature triaxial tests (operando method) enabled the analysis of the spatial distribution of deviatoric strain too. In both cases, maps show the relevant role of fibres orientation with reference to the shear band. If adequately activated, fibres tension modifies the strain field in the samples, preventing the fragile rupture along a shear plane and transferring the stresses to the outer soil portions, in this way providing a more dilatant and ductile overall response of the reinforced material.
Sand and silt treatment with novel binders
Authors: Spagnoli Giovanni , Fraccica Alessandro , Arroyo Marcos , Romero Enrique
Published: July 2024

An attractive approach to reduce the carbon footprint for ground improvement application is to replace Portland cementbased binders by non-cementitious binders for instance by geopolymers based on metakaolin in deep soil mixing applications or by colloidal silica and acrylates in permeation based applications. Safe design requires a good understanding of the mechanical and hydraulic properties of the improved ground but little is known about how soil is improved by these products. Besides, for permeation grouting applicability criteria are frequently set in terms of the host soil water permeability. However, for novel binders the threshold value is not known and published empirical basis for available criteria is relatively scarce. This paper summarizes results from a laboratory characterization campaign of soils of variable permeability improved with different novel binders, focusing on the effect on strength, stiffness and permeability. Observations relative to the effect of curing conditions are also provided, as well as the insight gained by examining the injection process outcomes with computed tomography. Results show how these novel products have the potential to significantly improve the mechanical properties and reduce permeability in a large range of soils.
Stabilization of an iron ore tailings by-product with perlite waste geopolymer
Authors: Melo de Deus Vieira Gabriella , Dal Toé Casagrande Michéle , Aguiar dos Santos Roberto
Published: July 2024

In the field of engineering, sustainable solutions that can generate lower environmental impacts, either through material replacement or reuse, are increasingly sought after. In Brazil, in the geotechnical area, there is a demand to find solutions to avoid the disposal of tailings sludge destined for structures, following the recent dam ruptures of Fundao in 2015 and Corrego do Feijao in 2019. One of the recent investments is in the treatment of tailings, generating by-products. To improve the mechanical properties of these by-products, geopolymer utilization has been employed. Geopolymers are products resulting from reactions between aluminosilicate precursors and alkaline activators. The objective of this study is to evaluate the unconfined compressive strength of an iron ore tailings by-product stabilized with a geopolymer that utilizes perlite waste as a precursor and sodium hydroxide as an activator through a two-part alkali-activation process. Two molar concentrations of activators, 2M and 5M, and two sample compositions were evaluated: one with 20% geopolymer and 80% iron ore tailings by-product, and another with 30% and 70%. An increase in unconfined compressive strength was observed with higher concentrations of the activator solution and a greater percentage of geopolymer in material stabilization. Thus, it can be stated that the use of geopolymers in by-product stabilization is promising, but finding the optimal dosage and evaluating other variables such as curing time and temperature is necessary.