bluuebunny/crossref_metadata_2025 huggingface dataset:
Why an indirect estimate of the unjacketed pore modulus may not work
Authors: Tarokh A , Labuz J F
Published: January 2023

The unjacketed pore modulus is a measure of changes in pore volume due to the variation in pore pressure for constant Terzaghi effective pressure. In the oil and gas industry, this parameter is commonly used in linking the undrained bulk modulus of a porous saturated rock to the drained bulk modulus and the properties of the fluid and solid components through Gassmann’s equation. For an ideal porous rock, the unjacketed pore modulus should be identical to the solid bulk modulus of the major mineral constituent. While direct measurements confirm this prediction, previous indirect estimates suggest that this parameter may have values close to the bulk modulus of the fluid rather than the bulk modulus of the grains. These indirect results demonstrate that the estimate of the undrained bulk modulus, due to substitution of different fluids in the rock, can change considerably if the unjacketed pore modulus is equal to the bulk modulus of the fluid. In this paper, we first briefly provide the results of the direct approach and then present laboratory measurements of Skempton’s pore pressure coefficient for a quartz arenite sandstone and use these data to indirectly estimate the unjacketed pore modulus. We show that the difficulties associated with the measurement of the Skempton coefficient clearly contribute to the underestimation from the indirect approach.
A review on the application of cohesive zone model in hydraulic fracturing
Authors: Li X J , Zhao H F , Xu K Q , He Y L , Wang C W , Yao W J
Published: January 2023

Hydraulic fracturing is an effective measure to increase production and injection and blockage removal in oil and gas field development. Accurate prediction of fracture morphologies is the key to the optimized design of hydraulic fracturing. The cohesive zone model (CZM) has been widely used in the numerical simulation of fracture initiation and propagation during hydraulic fracturing. The fractures formed by the numerical simulation vary significantly with different CZMs. In the current numerical simulation, the CZM generally adopts the bilinear model, which is more suitable for describing brittle fracture, while rocks are quasi-brittle materials and have nonlinear CZMs. This deviation should be corrected. Moreover, the CZM parameters are generally determined based on experience, without a reliable basis and standard determination method. This article focused on the CZM, systematically introduced its concept and classification, and clarified the correlation between the types of CZMs and the brittleness, quasi-brittleness, and ductility of rock fracture. The application of CZM in hydraulic fracturing was reviewed, and the existing problems, corresponding countermeasures and future research trends were presented. An integrated method of combining laboratory experiments, data mining and numerical simulation to determine the CZMs of mode I, mode II, and I/II mixed mode cohesive cracks was proposed.
A Bayesian regression analysis of in situ stress using overcoring data
Authors: Javaid M A , Harrison J P , Ivars D Mas , Kasani H A
Published: January 2023

Characterising the state of in situ stress at a target depth is crucial for all underground engineering projects. Consequently, on critical projects such as nuclear waste repositories extensive campaigns are implemented with the goal of estimating the in situ stress state. These campaigns often comprise both direct measurement and indirect estimation methods, but the data obtained across a project volume may exhibit significant variability. This poses significant challenges in both quantifying the variability and uncertainty of in situ stress, and determining the stress state to be used for design purposes.

It is often assumed that the state of in situ stress increases linearly with depth, and thus linear regression of principal stress magnitude against depth are often found in the literature. As such methods not honouring the tensorial nature of stress are, strictly, incorrect. To show how this limitation may be overcome, here we present a Bayesian regression analysis of in situ stress with depth that uses the Cartesian stress tensor. The analysis is performed using over 100 overcoring data obtained at the SKB Forsmark site in Sweden.

A comparison between the customary and Bayesian approaches is presented, which shows the superiority of the tensorial technique.
Energy Release Resulting from Sudden Excavation Shape Changes during Two-sided Strainbursts
Authors: Gonzalez F J , Kaiser P K , Diederichs M S
Published: January 2023

When tunnels in underground hard rock mines experience strainbursts, the effective shape of the tunnel suddenly changes as part of the rock fails, notches form and the broken rock bulks inside the strainburst volume. For circular tunnels, this dynamic rupture and bulking process causes a shape change with associated displacements and velocities in the surrounding elastic rockmass and at the excavation walls. This process can be approximated for circular tunnel bursting in elastic rock by a shape change from circular to elliptical and Maugi’s solution [1] can be adapted to estimate related displacements and average ground velocities. If these velocities are imposed on a volume of rock or shotcrete with a given mass, the mass can be ejected, and the corresponding kinetic energy can be estimated. When combined with the sudden bulking of the fractured rock, displacements and velocities are magnified between the elliptical shape and the pre-burst (circular) shape of the tunnel. This study focuses on the effect of the combined excavation response with elastic and bulking deformations to assess frequently observed excavation damage processes involving ‘shotcrete rain’ and heave of floor slabs caused by these shape changes. An analytical solution is presented for circular tunnels to estimate the elastic and bulking displacements, the resulting velocities, and energy demands.
A refined evaluation method for the stress field of the Chang 73 shale oil reservoir of northern Shaanxi
Authors: Zhang Yu , Hou Bing , Wang Yizhao , Ma Wenzhong , Dan Weidong , Zhuang Li
Published: January 2023

Shale oil resources are abundant in the Chang 73 reservoir in the eastern Ordos Basin. The thin interbeds of shale in the Chang 73 section of the Yanchang Formation in the oil-bearing section are developed with solid interlayer inhomogeneity and unclear longitudinal interlayer stress difference. This has resulted in unpredictable high seam extension heights during hydraulic fracturing. Based on the results of the Kaiser experiments, the lithological variability was finely described by combining with downhole core observations, and the longitudinal interlayer stress difference coefficient in the Chang 73 section was finely interpreted by using logging data to evaluate the regional distribution pattern of ground stress in the Chang 73 shale reservoir in northern Shaanxi. After studying 600 wells in north of Shaanxi, it was found that: the maximum longitudinal ground stress variation in the Chang 73 reservoir with a thickness of 30-50 m was 35-55 MPa, the minimum ground stress variation was 30-50 MPa, and the minimum was 30 MPa. The horizontal stress difference in the Chang 73 reservoir north of Shaanxi was 3.2-8.6 MPa. The maximum horizontal stress was high in the northwest and low in the southeast, with high values distributed in Jiyuan and Dingbian areas and low values distributed in Zhidan. The refined evaluation of the ground stress results guides the selection of the fracturing layer and the optimal design of the horizontal well trajectory in the field.
Assessment of static performance of welded mesh along mesh overlap used at Kiirunavaara mine
Authors: Zhang Ping , Eriksson Fredrik
Published: January 2023

Localized failure of mesh, i.e., the mesh was cut or torn by rock blocks as a result of a seismic event, was observed at LKAB’s Kiirunavaara mine. This is especially common along mesh overlap where mesh sheets are joined together. However, the performance of welded mesh along mesh overlap is not well understood. A series of tests was conducted at the laboratory at Luleå University of Technology, Sweden. The tested mesh sheets are made of 5.5 mm diameter wires welded along orthogonal directions spaced on a grid of 75 mm by 75 mm. The mesh sheet(s) was placed on a steel rig and fixed with bolts with spacing of 1.0 m by 1.0 m. A 300 mm loading plate made of concrete was placed underneath the mesh and pull/push load was applied on the mesh through the plate. For comparison purpose, the loading plate was placed at the mesh center following a dice five pattern as well as in the middle between two bolts (overlap position). The force-displacement curves of different test configurations were measured and failure modes of the mesh were observed. Laboratory test results show that the load-carrying and deformation capacity of the mesh is highly dependent on the load spreading and loading position relative to the holding points. When the mesh overlap was loaded, it shows: i) the highest stiffness; ii) the highest rupture load; iii) lower residual load-carrying capacity; and iv) the lowest deformation capacity. Two failure modes were observed in the conducted tests. Heat affected zone failure is the most common one and the second is the tensile failure along wires. Based on the laboratory results, an optimized mesh layout and bolting pattern was suggested for the Swedish underground mines.
Tunneling in heterogeneous ground: an update of the PBE code accounting for the uncertainty in estimates of block quantities from site investigations
Authors: Napoli M L , Barbero M
Published: January 2023

Hard rock blocks embedded in a soft matrix can be found in many geological units. When tunneling in these heterogeneous formations, many technical problems can be caused by the presence of cobbles and boulders. These risks depend on the excavation method selected, and typically increase as the block content, dimension and frequency increase. Therefore, successful tunneling projects require cobble-boulder properties to be accurately predicted, in order to select the best tunneling method and design the most appropriate cutterhead. A recent and extensive statistically-based methodology was developed to estimate the probability of encountering rock blocks located totally or partially within the tunnel excavation area, resulting in a free executable code, named PBE. A significant limitation of this code is that it requires, among other input parameters, the block content expected within the tunnel zone. This parameter can be estimated from 1D (i.e. borings/scanlines) or 2D (i.e. geological maps, outcrops, photographs) measurements. However, the block quantity inferred from these measurements is generally affected by a high magnitude of error. In this paper, an extension of the PBE is presented, that accounts for the uncertainty in estimates of block quantities from site investigations. The updated version of the executable code is also provided.
Laboratory study of the behaviour of grouted cable bolts under static and dynamic axial loading
Authors: Anzanpour S , Aziz N , Remennikov A , Nemcik J , Mirzaghorbanali A , Rastegarmanesh A
Published: January 2023

As a typical roof-supporting system of tunnels, Cable bolts are subjected to static and dynamic loading conditions caused by ground movements and mining activities. As mining goes deeper, the chance of undetermined ground stress concentrations increases and subsequently, the probability of sudden unexpected failures such as rock bursts increases. Many studies have been carried out to simulate the axial loading condition of the tendons, especially cable bolts, under static and dynamic loading modes; however, it barely can be seen that both behaviours have been studied and compared simultaneously. From other points of view, although research has been conducted on Barrel and Wedge and load-bearing plates, these components have hardly been considered together in axial loading studies. In this laboratory study, a new pullout testing mechanism has been introduced, which is capable of implementing axial loading of cable bolts in both static and dynamic loading conditions. In addition, in a parametric study, the role of bulbs of the cable bolts as well as barrel and wedges on the load-bearing capacity of the anchors have been examined. The bond between cable bolts and grout material in the bulbed cables behaves almost 30% stronger in static and 40% stronger in dynamic tests in comparison with plain cables. In general, the required pullout energy in dynamic tests was 25-50% less than in static tests.
Application of seismic sensors on measurement while drilling for real-time rock property detection
Authors: Khanal M , Shen B , Duan Y , Luo X
Published: January 2023

Rock type and geological structures are often characterized with geotechnical and geological data gathered from boreholes that are drilled considerable distances apart. Such characterization may not identify localized variations associated with rock mass. The continual acquisition of rock data while drilling on a local scale has a potential to provide confidence in detecting rock types and interpreting rock properties, and depending on the application, may inform downstream operations.

Drill returned parameters, such as, rotary speed, penetration rate, sound, torque, vibration, can provide insights into rock geotechnical properties. In the past, most of the researches in this area are limited to the use of conventional drill parameters such as penetration rate, rotary speed, torque and weight on bit. Noisy signals from drilling operations often pose a major challenge from using these conventional parameters to reliably interpret rock properties. To overcome this issue, in addition to the conventional drill parameters, the feasibility and application of seismic sensors on identifying relative rock properties have been explored in the current research. The interaction between the drill bit and rock mass being drilled generates seismic signals, which vary with different rock conditions and drilling operations. These seismic signals can be interpreted to detect rock types, rock properties, rock-ore interfaces and geological structures on a local scale.

Laboratory experiments with a rotary drilling machine on synthesized rock samples with and without interfaces have been conducted. Preliminary laboratory results show clear seismic signatures when drilling through the rocks with various strengths and interfaces. The results obtained using the conventional drill parameters and seismic data have also been compared in this paper.
Consideration of the mechanical behaviour and the influence on ground of vertical pre-reinforcement
Authors: Amemiya T , Nagata T , Isago N , Kawata K , Shiroma H , Nishimura K
Published: January 2023

The vertical pre-reinforcement bolt method is used to stabilize the ground at the top of tunnels with shallow overburden to prevent ground surface settlement and to stabilize slopes. However, the design of this method is mainly empirical, based on similar construction cases, and a quantitative design method has not been established. Model tests simulating the vertical pre-reinforcement bolt method and its numerical analysis were conducted to establish a rational design concept for the vertical pre-reinforcement bolt method. The results of the model test showed that the vertical pre-reinforcement bolt method can improve the continuity of the ground regardless of overburden and slope angle. It was found from numerical analysis that the spacing, width and properties of the bolts were related to the reinforcement effect.
Drilling boreholes in sulphureous groundwater areas: elements of some case studies in Portugal
Authors: Ferreira-Gomes L M
Published: January 2023

In Portugal there is a special market niche, which is the medical spa sector. These are supplied by special groundwater, being the sulphureous type water, the most frequent water in this activity. These waters essentially have a long geohydraulic circuit, associated to granite massifs, in confined to semi-confined aquifer systems of the fissural type, and natural discharge sites are often associated with structurally very complex areas, with faults sometimes of great thickness, that lead to sudden variations, from very fresh rock to clay. However, this situation is very favourable to unexpected collapses of the borehole under construction, with terrible problems to overcome, sometimes leading to involuntary deviations in the spatial position of the drilling in progress. On the other hand, because one of the current solutions is the use of cementations, associated with re-drilling, there is also the problem, of the difficulties of cement grouts in a common situation, not gaining strength, due to the chemical composition of sulphureous groundwater. It should be noted that these aquifer systems have the potential to provide natural hot water, when the boreholes reach great depths and can leverage geothermal uses, at the same time as uses in medical spas. Therefore, it is necessary to know these aquifer systems well, to lead to more efficient projects in the future. Therefore, in that sense, after presenting the typical chemical composition of the sulphureous groundwaters understudy, the experiences acquired in the drilling of some boreholes in Portugal, namely in the Carvalhal Medical Spa, Longroiva Medical Spa, Águas do Graben, Unhais da Serra Medical Spa, and the new mineral water of Granjal (Santa Comba Dão), are briefly presented. The comparison of the objectives defined at the beginning with the results obtained is generically presented, namely the depth of drilling, giving emphasis to the problems of collapse of the walls of the boreholes, cementing, additives, among others. At last, some final notes are presented in the sense that the drillings in this type of hydrogeological systems, in the future come to be increasingly efficient and reach greater depth, not only to acquire water with quality freer of interferences with fluids of superficial aquifers, but also, in the sense of reaching temperatures that make the use of geothermal energy viable.
A preliminary study of hydro-mechanical properties for bentonite-sand mixture
Authors: Motoshima T , Iso S , Nishimura T
Published: January 2023

Radioactive waste is a consequence of treatment radioactive material in industrial, medical, military and research applications for remaining electrical energy. For high-level waste (HLW), spent fuel (SF) and long-lived waste categories, geological disposal at depths of much hundreds of maters is considered in safety design. This study has aim to appear that swelling pressures due to hydration effort, hydraulic conductivity and stress-strain properties associated to evaluation to stress paths using two different bentonite-sand mixture, which are Sodium type bentonite and Calcium type bentonite. These materials have key feature in hydro-mechanical properties established in many reported obtained from laboratory test and underground investigations. Swelling pressure test, hydraulic conductivity test and triaxial compression test are conducted out, and developed apparatus are useful to results for series of some testing programs. Particularly, salinity concentration with increasing and decreasing on considering salinity effort is so interesting that further changing is applied to hydraulic conductivity for bentonite. While large lateral pressures are applied the bentonite at triaxial compression test, depending on lateral pressure is obviously to strength parameters that are apparent cohesion and angle of internal friction.
Verification of Spalling Tensile Strength of Rocks using 3D GPGPU-accelerated Hybrid FEM/DEM
Authors: Min G. , Fukuda D. , Oh S. , Liu H. , Cho S.
Published: January 2023

The spalling test is widely applied for evaluating dynamic tensile strength of rock under high strain-rate condition. The dynamic tensile strength is indirectly measured in the spalling test by theoretically assuming the tensile stress level at the failure position of a cylindrical specimen based on the 1D stress wave propagation theory. However, the theoretical estimation method for dynamic tensile strength have not been fully validated since dynamic tensile strength was determined with insufficient understanding of the fracture process, such as crack propagation and stress distribution in the rock specimen during the spalling test, owing to observational limitations in the experiment. Thus, a proper validation method is required for the proposed method, and numerical simulation can be used to validate the proposed method by reproducing the tensile fracture process of the rock specimen during the spalling test. Thus, the dynamic spalling tensile test for rock specimens was reproduced in this study using the GPGPU-based 3D hybrid FDEM that we recently developed. The dynamic tensile fracturing process was analyzed in the simulation of spalling under various strain-rate conditions. Finally, we discussed the application of various theoretical estimation methods to the 3D spalling test.
A brief review of the effect of wildfires on rockfall occurrence
Authors: Pérez-Rey I , Sarro R , Tomás R , Alejano LR , Gutiérrez LE Hernández , Mateos RM , Riquelme A
Published: January 2023

Wildfires and rockfalls are among the major hazards in forested mountainous regions across Europe. Understanding processes and conditions that lead to rockfalls during and after a wildfire in different geological contexts is, therefore, of great relevance. The increase of rockfalls associated with the occurrence of wildfires is connected to several factors, not only in the detached area but also in the propagation and affected area. Wildfires cause changes in the mechanical properties of rocks and discontinuities as well as the loss of protective capacity from vegetation, complemented by the effect induced by firefighting activities and by extreme temperatures that may deteriorate the installed protective measures. After the occurrence of a wildfire, there is an increase in the frequency and intensity of rockfalls in the burned area, causing a major impact of rockfalls on road networks and inhabited areas. Additionally, the rockfall risk perception is usually increased due to the removal of vegetation by wildfires, exposing both rock blocks and the rock mass. In this review, the main factors that influence the occurrence of rockfalls after a wildfire are briefly reviewed.
Discrete Element Method Simulation of Borehole Breakout Based on the Strain Energy Concept
Authors: Xiang Z , Oh J , Moon T , Si G , Li X , Canbulat I
Published: January 2023

This study focused on studying the V-shaped rock failure around borehole walls and reproducing borehole breakout using numerical simulations. Discrete element method (DEM) is adopted, and a two-dimensional particle flow code (PFC2D) model is built based on Tenino sandstone. The simulations are conducted by applying different maximum horizontal stress values under the same minimum horizontal stress condition, and the results are compared with the true-triaxial breakout experiments on the same rock properties and loading conditions. Due to the absence of vertical stress in 2D simulations, the obtained angular spans are generally larger than the experimental values. On the other hand, the breakout depths are found to be significantly smaller than the experimental results since the failed particles within the breakout zone remained to withstand internal loads and constrain the damage zone. In order to better simulate the rock detachment process during breakout formation, a particle removal algorithm using the strain energy release concept is developed and embedded into the model. With the implementation of the algorithm, the breakout propagation process in the vicinity of the borehole shows a good agreement with the experimental observations, suggesting that the effective removal of failed particles is essential for accurately simulating borehole breakout. The results from this study can provide new insights into the V-shaped breakout formation mechanism and strain energy changes during borehole breakout initiation and propagation.
Riskcoast: A South-European approach for coastal landslide hazard: presentation and results
Authors: Gasc-Barbier M , Thiery Y , Garnier C , Raveneau L , Bernardie S , Chanal A
Published: January 2023

RISKCOAST is a European project, co-funded by the South-West European (SudOE) Interreg V programme (https://riskcoast.eu), which aims to develop tools to prevent and manage coastal geological risks related to global warming: land movements mainly, but also other phenomena such as the evolution of water tables. The aim of this project is to study geological risks in coastal areas related to climate change, with a focus on improving the coordination and effectiveness of means of prevention, disaster management and rehabilitation of disaster areas. After a presentation of the whole project, we will focus on a specific site in the French Basque coast where a landslide impacts a very touristic area. An hydrogeomechanical model of the landslide is realized with FLAC3D and a parametric study is proposed to determine the most important parameters, and to define possible safety factor game value.
Experiences and preliminary results of geophysical methods on historical statues
Authors: Vagnon Federico , Comina Cesare , Canepa Marie Claire , Bovero Alessandro , Giraudo Giuseppe
Published: January 2023

In recent years, geophysical applications have been significantly grown in rock mechanics field due to their versatility and reliability as diagnostic and/or monitoring tools. Since these methodologies are mainly non-invasive, they can be used for the investigation and characterization of the internal structure of historical artworks or for the monitoring of built cultural heritage, where the non-destructive feature is an indispensable prerequisite. Commonly, the artworks material properties are unknown or strongly altered due to time and physical/chemical agents. Moreover, their nature (mineralogic and petrographic) and origin (in terms of places where the material was exploited) is uncertain and difficult to allocate. Among the available geophysical techniques, seismic methods are useful for detecting the thickness or position of weathered layers, for estimating the physical properties of different materials and for providing information about cracking and degree of fracturing. In this paper, we present some experiences and preliminary results of geophysical characterization of two Tritons statues, discovered in the garden of the Royal Palace of Venaria (Piedmont Region, Italy). The statues were originally part of the Fountain of Hercules, destroyed in the 18th century during the redevelopment works of the Palace. Ultrasonic pulse velocity measurements were performed on each portion of the statues and 3D-imaging of the apparent P-wave velocity were carried out. The performed geophysical investigations were aimed at defining the overall material quality and detecting possible sectors with low resistance properties that might interfere with the coring operations, necessary for the reassembly of the statues. Results of these surveys were also useful for setting up a 3D-FEM model for simulating the material behaviour through an analysis of the forces and loads involved.
Fluorine-free and ultra-thin films prepared by RF-PECVD method for the anticorrosive applications
Authors: Wu Liting , Liu Luqi , Ma Fuliang , Shen Luli , Wang Gang , Zeng Zhixiang , Wu Xuedong
Published: January 2023

The high-reliability requirement of 5 G electronic products poses a higher challenge to its protective films, the high transmission quality of high-frequency signals, excellent heat dissipation and anticorrosive capability, which promotes the ultra-thin protective films with good adhesion and anticorrosion. In this work, a nanometer-scale p-HMDSO film was obtained on the Cu alloy with hexamethyldisiloxane (HMDSO) as the precursor by the low-temperature RF-PECVD method. Compared with Parylene and p-PFDA (1H, 1H, 2H, 2H-Perfluorodecyl acrylate) films, the p-HMDSO film possesses better hydrophobicity, mechanical stability and anticorrosive property. The corrosion inhibition efficiency of the p-HMDSO film reaches 99.95%. Meanwhile, it provides 3 orders of magnitude increment of charge-transfer impedance, a salt spray corrosion resistance for 24 h, and the protection of 10 days in the 3.5 wt% NaCl solution, which develops a better application prospect in the protection of integrated electronics.
Carrier mobility and high-field velocity in 2D transition metal dichalcogenides: degeneracy and screening
Authors: Iglesias José M , Nardone Alejandra , Rengel Raúl , Kalna Karol , Martín María J , Pascual Elena
Published: January 2023

The effect of degeneracy and the impact of free-carrier screening on a low-field mobility and a high-field drift velocity in MoS2 and WS2 are explored using an in-house ensemble Monte Carlo simulator. Electron low field mobility increases to

8400

c
m

2

V

−
1

s

−
1

for MoS2 and to

12
040

c
m

2

V

−
1

s

−
1

for WS2 when temperature decreases to

77

K

and carrier concentration is around

5
×

10

12

c
m

−
2

. In the case of holes, best mobility values were

9
320

c
m

2

V

−
1

s

−
1

and

13
290

c
m

2

V

−
1

s

−
1

, reached at similar temperature and carrier concentration conditions while at room temperature these fall to

80

c
m

2

V

−
1

s

−
1

and

150

c
m

2

V

−
1

s

−
1

for MoS2 and WS2, respectively. The carrier screening effect plays a major role at low fields, and low and intermediate temperatures, where a combination of large occupancy of primary valleys and carrier–phonon interactions dominated by relatively low energy exchange processes results in an enhanced screening of intrinsic scattering. For electrons, degeneracy yields to transport in secondary valleys, which plays an important role in the decrease of the low field mobility at high concentrations and/or at room temperature. The high-field drift velocity is not much affected by carrier screening because of an increased carrier scattering with surface optical polar phonons, favouring larger phonon wavevector interactions with small dielectric function values.
High-performance flexible broadband photodetectors enabled by 2D Ta2NiSe5 nanosheets
Authors: Guo Tingting , Sa Zixu , Wei Pengfei , Jian Yuxuan , Chen Xiang , Chen Zhesheng , Avila Jose , Dudin Pavel , Yang Zai-xing , Song Xiufeng , Liu Fengjing , Zhang Shengli
Published: January 2023

Flexible broadband optoelectronic devices play a prominent role in the areas of daily life including wearable optoelectronic systems, health care, and bio-imaging systems. Two-dimensional (2D) narrow-bandgap materials with atomic thickness, adjustable bandgap, mechanical flexibility, as well as excellent optical and electrical properties exhibit great potential for applications in flexible optoelectronic devices. Here, we demonstrate a high-performance photodetector based on high-quality ternary Ta2NiSe5 nanosheets with a narrow bandgap of 0.25 eV. The photodetectors exhibit broadband photodetection capability in the visible-infrared (IR) spectrum (405–2200 nm) at room temperature. The maximum values of responsivity can reach up to 280 A W−1 at the wavelength of 405 nm. Meanwhile, the high responsivity of 63.9 A W−1 and detectivity of 3.8 × 109 Jones are achieved at the wavelength of 2200 nm, respectively. In addition, the obtained Ta2NiSe5-based photodetector shows excellent flexibility and the photodetection performance is almost insignificantly degraded after 1000 bending cycles. These results indicate that the 2D Ta2NiSe5 semiconductor has great potential in future wearable IR optoelectronic devices.
Investigation on electrochemicl behavior of modified Al anodes in tidal environment of shengli oilfield
Authors: Yang Chao , Wang Zenglin , Wang Guanjun , Han Qing , Liu Haibo
Published: January 2023

Al anode was widely used for cathodic protection of metal in marine environment due to its high capacitance and current efficiency. However, it was prone to passivation in alternating dry-wet environments. At present, relevant scholars had carried out research on new Al anodes in the alternating dry-wet environment of atmosphere or ocean. However, there were few reports on Al anodes in the soil alternating dry-wet environment. Therefore, focusing on the tidal environment of Shengli oilfield, the performance of three types of modified Al anodes was determined by corrosion and electrochemical test. The results showed that compared with Al-2 and Al-3 anodes, the corrosion product layer on the surface of Al-1 anode showed a broken, loose, poor compactness characteristic, while the general corrosion rate (4.329 mm/a) was larger and the maximum pit depth (27 μm) was smaller on the 30th day of immersion experiment. Meanwhile, the open-circuit potential of Al-1 anode (E
OCP = −1.09 V) was more negative, and the corrosion current density (I
corr = 5.34 × 10−3
μA m−2) was larger, while the capacitance (Q-Y
0 and C
dl) was larger and the resistance (R
p and R
ct) was smaller. In conclusion, the Al-1 anode showed a better performance in tidal environment of Shengli oilfield.
Effect of various fuels used in combustion synthesis on the bioactivity of akermanite
Authors: Kothandam Shobana , Swamiappan Sasikumar
Published: January 2023

Significant interest has been inspired by the exceptional biological performance of akermanite bioceramic in tissue engineering. This exertion investigates effect of fuel on the biomineralisation using three different fuels viz., glycine, L-alanine, and urea. The materials were prepared through sol-gel combustion method by using Glycine, L Alanine and Urea as a fuel and encoded as AK-G, AK-AL, and AK-U. The mechanism associated in the synthesis of these bioceramic was examined by thermal analysis. The pure phase achieved at 900 °C was confirmed by powder XRD, the functional groups were identified by FTIR analysis. When glycine was employed as the fuel, the average crystallite size formed was 32–36 nm; however, for alanine and urea, shows increase in value of 34–40 and 37–43 nm, respectively. Surface morphology and elemental composition were confirmed by SEM/EDX. AFM analysis indicates that Glycine imparts higher surface roughness than other ceramic materials, which promotes nucleation of hydroxyapatite during biomineralization. Among the three samples, AK-Glycine exhibits considerable improvements in bioactivity with a Ca/P ratio of 1.60 which is closer to natural hydroxyapatite (1.67) and makes it an appropriate candidate for bone tissue engineering applications.
Biodegradable cow dung for brake friction material: a preliminary investigation
Authors: Balaji N , Elgorban Abdallah M , Bahkali Ali H , Zaghloul Nouf S S
Published: January 2023

The purpose of the study is to develop a biodegradable and non-asbestos/copper-free brake pad formulation. The possibility of using organic cow dung particles as an eco-friendly reinforcement in friction material for brake pads is investigated. Sodium hydroxide (NaOH) treated cow dung is Sun dried and ground to an average particle size of 200 microns. It is reinforced in epoxy resin in weight fractions of 5%, 10%, 15%, 20% and 25% along with other fillers and friction stabilizers. The composite samples are subjected to density, thermal conductivity, microhardness and tensile strength evaluation for mechanical characterization. Pin on disc testing is done to identify the coefficient of friction (CoF), wear coefficient and specific wear rate as a part of tribological characterization. The scanning electron micrographs and EDAX analysis of worn out surface is performed to study the wear mechanism. Promising results are seen with composite samples reinforced with 15% cow dung particles in terms of better microhardness, tensile strength, stable coefficient of friction and low wear. The investigation could guide industries working on brake pad materials. This could open up an era of low cost, organic and eco-friendly alternative to carcinogenic asbestos/copper in friction materials.
A new method for simulating electron beam welding process of niobium sheets with beam oscillation
Authors: Tao Jia , Wu Jiefeng , Liu Zhihong , Ma Jianguo , Liu Zhenfei
Published: January 2023

Oscillating electron beam welding (EBW) is necessary for the fabrication of pure niobium superconducting radiofrequency (SRF) cavities. Due to the negative effects that welding deformation and residual stress have on the performance of the SRF cavities, it is crucial to predict residual stress and welding distortion with high precision for the design of welding tooling and the optimization of welding parameters. However, the stress and distortion simulation of oscillating EBW received little attention in the previous research. In order to accurately predict the welding stress and distortion of niobium cavities with thin walls, a novel heat source with two reverse 2D Gaussian heat sources was used for the first time in the finite element method (FEM) simulation of EBW with beam oscillation. Additionally, a computational fluid dynamics (CFD) simulation of the molten pool was run as a guide for adjusting the parameters of the designed heat source. The FEM simulation with 2D Gaussian heat source was taken as a comparison. An EBW experiment of niobium sheets was performed to verify the simulation. The simulated molten pool of this model has a wider width, which is significantly closer to the actual measurement. Compared with the result estimated by 2D Gaussian heat source. The joint simulated with the designed heat source displays a smoother temperature gradient. The mechanical results suggest that the peak longitudinal stress in the weld center, the peak transverse stress in the weld center, the longitudinal contradiction, and the transverse contradiction estimated by the designed model deviate from the experimental results by only −4.88%, −4.03%, −9.32%, and −5.98%, respectively. The error of the simulation by the proposed method is dramatically smaller than the evaluation by the 2D Gaussian model. The designed heat source and the CFD validation provides a reliable simulation scheme for the oscillating EBW of thin sheets, and the oscillating EBW of thick plates will be simulated using the suggested method with the improvement of the heat source model in the future.
Preparation, enhancement of permeability, and anti-biofouling properties of PEES/nano-silver/PVP mixed-matrix membrane
Authors: Soundarrajan M , Alibrahim Khuloud A , Krishnamurthi J , Maheswari P , Harikrishnan A , Alodhayb Abdullah , Muthumareeswaran M R
Published: January 2023

This study investigated the separation of bovine serum albumin using a novel matrix mixed membrane composed of poly vinyl pyrrolidone and poly (phenylene ether ether sulfone)/Nano-silver. The responsive bare and modified PEES/Nano-silver membranes were evaluated using morphology, wettability, XRD and ATR-FTIR. The molecular weight cut-off (MWCO), water content, mean pore radius, porosity, and pure water flux were used to evaluate the presentation of mixed matrix membranes. The outcomes show that the membranes wettability is increased by the addition of PVP, which promotes the formation of hydrogen bonds. Its clear that the membranes are more hydrophilic than the PEES/Nano-silver membrane based on their performance. In addition, model foulants such bovine serum albumin (BSA) andE. coliwere used to assess the efficacy of mixed matrix membranes anti-fouling properties. PVP loading results in more diversified surface morphology with asymmetric structure and higher water flux (4.35 × 10−5ms−1) than the pristine membrane (2.23 × 10−5ms−1) as a reference at 3.5 bar without compromising the rejection of membrane. The flux recovery ratio for PEES/PVP/Nano-Silver membranes is 97%, which is significantly higher than the ratio for PEES/Nano-Silver membranes (62%). Furthermore, The results of fluorescence microscopy showed that, compared to clean membranes, the modified membranes have biofouling activities.
Can we explain machine learning-based prediction for rupture status assessments of intracranial aneurysms?
Authors: Mu N , Rezaeitaleshmahalleh M , Lyu Z , Wang M , Tang J , Strother C M , Gemmete J J , Pandey A S , Jiang J
Published: January 2023

Although applying machine learning (ML) algorithms to rupture status assessment of intracranial aneurysms (IA) has yielded promising results, the opaqueness of some ML methods has limited their clinical translation. We presented the first explainability comparison of six commonly used ML algorithms: multivariate logistic regression (LR), support vector machine (SVM), random forest (RF), extreme gradient boosting (XGBoost), multi-layer perceptron neural network (MLPNN), and Bayesian additive regression trees (BART). A total of 112 IAs with known rupture status were selected for this study. The ML-based classification used two anatomical features, nine hemodynamic parameters, and thirteen morphologic variables. We utilized permutation feature importance, local interpretable model-agnostic explanations (LIME), and SHapley Additive exPlanations (SHAP) algorithms to explain and analyze 6 Ml algorithms. All models performed comparably: LR area under the curve (AUC) was 0.71; SVM AUC was 0.76; RF AUC was 0.73; XGBoost AUC was 0.78; MLPNN AUC was 0.73; BART AUC was 0.73. Our interpretability analysis demonstrated consistent results across all the methods; i.e., the utility of the top 12 features was broadly consistent. Furthermore, contributions of 9 important features (aneurysm area, aneurysm location, aneurysm type, wall shear stress maximum during systole, ostium area, the size ratio between aneurysm width, (parent) vessel diameter, one standard deviation among time-averaged low shear area, and one standard deviation of temporally averaged low shear area less than 0.4 Pa) were nearly the same. This research suggested that ML classifiers can provide explainable predictions consistent with general domain knowledge concerning IA rupture. With the improved understanding of ML algorithms, clinicians’ trust in ML algorithms will be enhanced, accelerating their clinical translation.
Ion dynamics in laser-produced collisionless perpendicular shock: one-dimensional particle-in-cell simulation
Authors: GUO Ao , TANG Huibo , REN Junyi , HU Guangyue , LU San
Published: January 2023

Recently, perpendicular shocks have been generated in laboratory experiments by the interaction between a laser-produced supersonic plasma flow and a magnetized ambient plasma. Here, we explore the ion dynamics and the formation of such kinds of shock with a one-dimensional (1D) particle-in-cell simulation model using achievable parameters for laser experiments. A small part of the ambient ions is first reflected by the laser-driven piston. These piston-reflected ions interact with the upstream plasma and form a shock then. By analyzing the contribution of the electric force and the Lorentz force during the reflection, shock-reflected ions are found to be accelerated by two different mechanisms: shock drift acceleration and shock surfing acceleration, where shock drift acceleration is the dominant one. Very few ions are reflected twice by the shock and accelerated to a large velocity, implying that a more energetic population of ions can be observed in future experiments.
Octopus-inspired glove grabs underwater objects using LIDAR
Authors: Dumé Isabelle
Published: January 2023

Inspired by the skin on octopus arms, researchers at Virginia Tech in the US have developed a new rapidly switchable adhesive that sticks securely to objects underwater.
Open-source tool calculates labs’ carbon footprint
Authors: Hiscott Laura
Published: January 2023

Researchers in France have developed a new open-source tool to help scientists understand and reduce the carbon footprint of their labs.
Early-career researchers in large groups more likely to leave academia
Authors: Hiscott Laura
Published: January 2023

According to a study, early-career researchers are more likely to drop out of academia if they are working with successful mentors who lead large groups.
Collaborate across multiple fields to be highly cited
Authors: Allen Michael
Published: January 2023

An analysis of more than 3000 scientists who publish in physical-science journals finds that those who repeatedly collaborate across multiple research disciplines produce papers that are more highly cited.
A cosmic tarantula is captured by NASA’s James Webb Space Telescope
Authors: Banks Michael
Published: January 2023

NASA and partners have released a spectacular image of the Tarantula nebula as taken by the James Webb Space Telescope.
Car-crash concerns
Authors: Lambourn Richard
Published: January 2023

A response to the article “Newton’s laws and carcrash claims”, in which Michael Hall looked at how simple classical physics can help weed out fraudulent vehicle insurance claims.
The iron rule of science
Authors: Follows Mike
Published: January 2023

Mike Follows reviews The Knowledge Machine: How an Unreasonable Idea Created Modern Science by Michael Strevens.
A school student’s week at CERN
Authors: Gill Annabelle
Published: January 2023

A week-long visit to the CERN particle-physics laboratory for Annabelle Gill not only revealed the many fascinating experiments housed there – but also highlighted the huge variety of jobs on offer for science students at big international facilities.
Turning molten glass into science art
Authors: Tesh Sarah
Published: January 2023

The Netflix TV series Blown Away demonstrates the immense strength, skill and determination needed to manipulate molten glass into any recognizable form, let alone a piece of art.
LED streetlights responsible for blue-light pollution in Europe
Authors: Cooper Keith
Published: January 2023

The shift to LED street lighting is producing more blue-light pollution, according to satellites that monitor night-time lighting.
Supercomputer simulations reveal how the Sun accelerates charged particles
Authors: Jackson Kevin
Published: January 2023

Researchers in the US have used supercomputers to gain insights into the origins of the solar wind.
Spectacular comet image wins Royal Observatory Greenwich prize
Authors: Banks Michael
Published: January 2023

Austrian astrophotographer Gerald Rhemann has won 2022 Astronomy Photographer of the Year with a photograph of a piece of Comet Leonard’s gas tail being disconnected and carried away by the solar wind.
Machine learning can predict a scientist’s gender from citation data
Authors: Hiscott Laura
Published: January 2023

A study has found that men and women have different citation patterns, making it possible to accurately predict a scientist’s gender from citation data alone.
Female physicists’ papers referenced less, finds study
Authors: Hiscott Laura
Published: January 2023

Female physicists are significantly under-cited compared to their male counterparts, according to an analysis of more than a million physics research papers.
Climate change will damage astronomical observations
Authors: Allen Michael
Published: January 2023

An analysis of changing trends in observing conditions across eight worldwide sites suggests that climate change will negatively impact the quality of ground-based astronomical observations.
Rainer Weiss: 50 years of LIGO and gravitational waves
Authors: Perkowitz Sidney
Published: January 2023

As one of the key experimentalists to conceptualize and then build one of the biggest experiments in history, Nobel-prize-winning physicist Rainer Weiss’s path to success is remarkable. Now aged 90 he talks to Sidney Perkowitz about his life and work, from the unexpected sources for scientific inspiration to the challenges of large-scale experiments.
Ask me anything: Jenni Strabley
Authors: Commissariat Tushna
Published: January 2023

Jenni Strabley is the senior director of offering management at global quantum-tech company Quantinuum, which offers quantum computing hardware and software solutions.