Combined Micro Research Articles

Mechanical characteristics and constitutive model of cemented tailings backfill under temperature-time effects

The increase in original rock temperature during the deep metal mine backfill mining process significantly impacts the mechanical properties of cemented tailings backfill (CTB). Uniaxial compression experiments were conducted under various curing temperatures and times, analyzing their mechanical characteristics based on strain energy. The experimental results indicate that the mechanical properties of CTB are significantly affected by temperature. The uniaxial compressive strength (UCS) follows a quadratic trend, initially increasing and then decreasing as the curing temperature changes. At the curing temperature of 40 °C, the hydration reaction of CTB develops fully, the hydration products have strong compactness, and the energy absorbed when failure occurs is the largest. The CTB is divided into a solid framework and pore sections to develop a constitutive damage model using a combined macro and micro experimental approach. Polynomial functions represent the correlation between the damage model parameters and curing time and temperature, resulting in a unified temperature-time damage constitutive model. Using the secondary development platform in FLAC3D finite difference software, the damage constitutive model of the CTB was further developed and integrated into the software, enabling both its development and application. This customized model provides a more comprehensive representation of the overall deformation and failure mechanisms of the CTB during compression. The study can predict the strength of CTB under different curing conditions, and provide theoretical reference for the simulation research of filling mining in mines.

Electrochemically fast preparation of superhydrophobic copper mesh for high-efficiency oil spill adsorption and oil-water separation

Oily wastewater and marine oil spills are a massive environmental and human threat. Conventional oil spill treatment methods include adsorption by absorbent materials, dispersants or adsorbents, and in situ burning. Superhydrophobic materials, as a material that can achieve oil-water separation, have great potential for application in oil spill treatment. Research on superhydrophobic oil spill treatment mainly focuses on materials such as sponges and fabrics. Although these materials can effectively perform oil-water separation or oil spill adsorption, they also have the disadvantages of complicated preparation methods and high costs. Here, we present a miniature device for oil-water separation and oil spill collection and recovery. The superhydrophobic copper mesh box can be used on its own as an oil-water separation device or in combination with a commercial polyurethane sponge as a miniature oil-absorbing device. The robust copper mesh is prepared in two steps: anodizing and impregnation. The superhydrophobic copper mesh had a high oil separation flux (32,330 L m−2 h−1) and efficiency (97%), which remained high (28,560 L m−2 h−1) and efficient (95%) after 20 cycles of separation. The combined micro oil adsorption device can adsorb different oils and fats on the water surface, and it has good reusability with oil adsorption capacity and efficiency up to 15.28 g/g and 98% and still has good oil adsorption capacity (11.54 g/g) and efficiency (94.6%) after 20 cycles of adsorption. Therefore, the prepared micro oil-absorbing device has promising application prospects in oil-water separation, oil spill cleanup, etc. Environmental ImplicationThis study demonstrates a facile electrochemical approach to prepare a miniature device for high-efficiency oil-water separation and oil spill collection and recovery. The modified copper mesh's separation flux could reach 32,330 L m−2 h−1, showing great promise in oil-water separation and oil spill cleanup.

Multiscale evaluation of hydrogen-assisted mechanical degradation in grade 2 titanium

The mechanism of hydrogen embrittlement in grade 2 titanium was studied by a combined micro and nanoscale approach. Insights into the hydrogen related deformation and degradation mechanisms were acquired via a unique characterisation procedure, correlating the topological observations on the fracture surface after tensile testing to the dislocation arrangement underneath. Focused ion beam lift-out was employed to extract a subsurface slice perpendicular to the fracture surface. High resolution characterisation provided information about the dislocation configuration and active hydrogen-assisted degradation mechanism. A high hydrogen content forms a brittle titanium hydride phase, failing via hydride cleavage. At a moderate hydrogen quantity, hydrogen in solid solution is responsible for a ductility decrease via the hydrogen-enhanced localised plasticity mechanism.

Effect of micro–nano bubbles on the remediation of saline–alkali soil with microbial agent

The widespread distribution of saline–alkali soil around the world affects the health of ecological systems and the development of the national economy by limiting the growth of plants. However, the commonly used remediation technologies have the drawbacks of low efficiency, high cost, and secondary pollution. This study investigated the feasibility and efficacy of novel combined micro–nanobubbles (MNBs) and microbial agent (MA) technology for the remediation of saline–alkali soil. The results demonstrated that the combined MA–MNBs method greatly renovated the properties of saline–alkali soil compared with the technologies of single utilization of MA or MNBs process in the laboratory. The method resulted in a reduction of soil electrical conductivity and pH levels, an improvement in soil fertility, and the formation of soil aggregates. Moreover, the method significantly impacted the growth of plants, particularly in plant length, dry weight, and rhizome elongation. Further high–throughput sequencing and gene expression analysis revealed that the MA–MNBs method enhanced the abundance of soil microbial community compared with single MA and MNBs treatment. Gene enrichment analysis revealed that the MA–MNBs method could compensate for the shortcomings of single MA treatment and enhance the expression of energy metabolism and salt stress–related genes attributed to MNBs treatment, thereby significantly improving the growth and development of plants. Consistently, 6115 kg/ha of rice was yielded in the field for the saline–alkali soils using this MA–MNBs method, with zero crops before remediation. This study provided a novel, efficient, and green strategy for the remediation of saline–alkali soil without adding any chemicals.

Soil protists are more resilient to the combined effect of microplastics and heavy metals than bacterial communities

Heavy metals and micro-/nanoplastic pollution seriously threaten the environment and ecosystems. While many studies investigated their effects on diverse microbes, few studies have focused on soil protists, and it is unclear how soil protists respond to the combined effect of micro-/nanoplastics and heavy metals. This study investigated how soil protistan and bacterial communities respond to single or combined copper and micro-/nanoplastics. The bacterial community exhibited an instantaneous response to single copper pollution, whereas the combined pollution resulted in a hysteresis effect on the protistan community. Single and combined pollution inhibited the predation of protists and changed the construction of ecological networks. Though single and combined pollution did not significantly affect the overall community structure, the exposure experiment indicated that combined pollution harmed soil amoeba's fitness. These findings offer valuable new insights into the toxic effects of single and combined pollution of copper and plastics on soil protistan and bacterial communities. Additionally, this study shows that sequencing-based analyses cannot fully reflect pollutants' adverse effects, and both culture-independent and dependent methods are needed to reveal the impact of pollutants on soil microbes.

Comparison of forming processes for micro textured cups

Friction losses are present in all kinds of technical systems. This is always associated with additional energy consumption, which can be partly avoided as it arises. Energy savings can be achieved by a wide range of approaches. The application of friction reducing coatings on bodies in relative motion is widespread. The coating of parts is however only suitable to a limited extent for the production in large batches. Therefore, research approaches consider alternative methods to achieve friction reductions. A promising approach is the integration of miniaturized pockets on the surface of the component. In lubricated contacts, the lubricant can then accumulate in these indentations. The relative motion between two bodies thus builds up a hydrodynamic pressure and consequently reduces friction. Forming technology is suitable for the efficient production of metallic components in large quantities. The aim of this study is therefore to identify challenges in the integration of micro coining in established forming processes. Two processes from sheet metal forming and bulk metal forming are investigated. In a combined experimental and numerical approach, process-specific challenges are derived regarding the texturing process and the numerical process modelling for combined micro coining. The analysis is carried out on a cup geometry, as used in the automotive sector as tappets in the valve train. The case hardening steel 16MnCr5 (1.7131) is used as workpiece material.

Tailoring the extrinsic porosity of a vapochromic metal–organic polyhedron for rapid VOC detection

Metal-organic polyhedra (MOPs) are intrinsically porous building blocks for the bottom-up construction of hierarchically porous materials. Herein, we report the syntheses of unprecedented solvato- and vapochromic MOP (DGIST-8) nanocrystals and aerogels, each exhibiting a different permanent porosity. Notably, the DGIST-8 aerogels with combined micro-, meso-, and macropores underwent unprecedented color changes perceivable to the naked eye after exposure to volatile organic compounds in both liquid and vapor phases. The key to achieving rapid and reversible vapochromic behavior involves a well-preserved high surface area that ensures the enhanced diffusion of solvent molecules due to the combined presence of micro-, meso- and macropores. The design principles of the vapochromic MOP aerogels disclosed in this report facilitate the use of MOPs as a new type of sensing material.

Characterization of Adipose-Derived Mesenchymal Stem Cells from tissue harvested with the guided SEFFI technique and co-cultured with calcium hydroxyapatite

Increased interest in regenerative medicine in the last few years was registered. In parallel, a progressive increase in injectable calcium hydroxylapatite (CaHA) applications has been observed due to its applications in skin rejuvenation. This study combined micro fragmented fatty tissue (FAT) grafting with the CAHA filler procedure to observe the biological effect on FAT. Each sample of micro fragmented adipose tissue harvested using the guided Superficial Enhanced Fluid Fat Injection (guided SEFFI) technique were collected from 5 patients. The 5 samples were divided into aliquots to create two different experimental conditions: FAT and FAT combined with CaHA (FAT + R). Afterwards, the cellularity of mesenchymal phenotype and the in vitro differentiation capacity in mesenchymal lineages were assessed in both experimental conditions, FAT and FAT+R. Despite low cellularity observed for FAT+R compared to FAT, isolated cells could grow and expand in culture in both experimental conditions, thus proving their proliferative ability. Cells were proved to differentiate towards mesenchymal lineages, expressing mesenchymal markers by flow cytometry analysis. Combining emulsified harvested tissue prepared with guided SEFFI technique with CaHA products can be exploited to counteract the loss of volume and skin ageing of the human face and body. This approach to regenerative aesthetic treatment is a promising treatment for facial antiaging therapy.

Improved wear resistance of cemented carbide impact needle under high frequency micro-amplitude impact treated by high current pulsed electron beam

Assembly and packaging technology is one of the most critical factors that restrict the development of microelectromechanical systems (MEMS), including chips and other devices. Dispensing robot is a key high-end equipment in MEMS packaging. Its core component, WC-Co impact needle, is limited by fretting wear and deformation, leading to reduced service accuracy and life, which is the most important cause of failure. Impact fretting wear frequently occurs in micro-nano mechanical systems and has been widely studied. However, the combined high frequency (∼300 HZ) and micro impact amplitude (∼120 μm) wear behaviors such as WC-Co impact needle with ultrafine grain (∼100 nm) is rarely concerned. To further understand the influence of impact frequency and impact velocity on the wear rate of impact needle, dispensing experiments were designed and the wear mechanism was investigated. Results indicated that the impact velocity has more influence on the wear rate of impact needle than the impact frequency. In addition, a high-current pulsed electron beam (HCPEB) surface treatment method which can effectively increase the wear resistance of impact needle was proposed. After HCPEB treatment, the abrasion loss was reduced by 44% compared to the untreated one at the same impact frequency and different impact velocities, while the abrasion loss was reduced by 52% compared to the untreated one at the same impact velocity and different frequencies. These can be attributed to the fact that HCPEB treatment decreased the grain size of WC-Co cemented carbide impact needle and promoted WC phase transition, leading to an increase in microhardness.

Accuracy of combined serum micro RNA 21 and micro RNA let 7g expression level in breast cancer diagnosis

Accuracy of combined serum micro RNA 21 and micro RNA let 7g expression level in breast cancer diagnosis

Estimating the mode I through-thickness intralaminar [formula omitted]-curve of unidirectional carbon fibre-reinforced polymers using a micromechanics framework combined with the size effect method

A three-dimensional micromechanics framework is developed to estimate the mode I through-thickness intralaminar crack resistance curve of unidirectional carbon fibre-reinforced polymers. Finite element models of geometrically-scaled single edge notch tension specimens were generated. These were modelled following a combined micro-/meso-scale approach, where the region at the vicinity of the crack tip describes the microstructure of the material, while the regions far from the crack tip represent the mesoscopic linear-elastic behaviour of the composite. This work presents a novel methodology to estimate fracture properties of composite materials by combining computational micromechanics with the size effect method. The size effect law of the material, and consequently the crack resistance curve, are estimated through the numerically calculated peak stresses. In-depth parametric analyses, which are hard to conduct empirically, are undertaken, allowing for quantitative and qualitative comparisons to be successfully made with experimental and numerical observations taken from literature.

A significantly improved polymer||Ni(OH)2 alkaline rechargeable battery using anthraquinone-based conjugated microporous polymer anode

Alkaline rechargeable batteries (ARBs) are predicted to be an attractive solution for large-scale electrochemical energy storage applications. However, their advancement is greatly hindered by the lack of high-performance and sustainable anode that can stably operate in less-corroding, low electrolyte concentration. Herein, we report the first example of polymer ARB able to operate in low concentrate electrolyte (1м potassium hydroxide [KOH]) due to the employment of a robust anthraquinone-based conjugated microporous polymer (IEP-11) as anode. The assembled IEP-11||Ni(OH)2 achieves high cell voltage (0.98 V), high gravimetric/areal capacities (150 mAh/g/7.2 mAh/cm2 at 3.5 and 65 mg/cm2, respectively), long cycle life (22,730 cycles, 960 h, 75% capacity retention at 20C), excellent rate performance (75 mAh/g at 50C) and low temperature operativity (75 mAh/g at −10 °C). Furthermore, rate capability, low-temperature performance and ability to prepare high mass loading anodes, along with low self-discharge is improved compared to conventional linear poly (anthraquinone sulfide) (PAQS) in commonly used 10 м KOH. This overall performance for IEP-11||Ni(OH)2 is not only far superior to that of PAQS||Ni(OH)2 owing to porous polymer's high specific surface area, combined micro-/mesoporosity and robust and mechanically stable three-dimensional (3D) architecture compared to the linear PAQS, but also surpass most of the reported organic||nickel [Ni]/cobalt [Co]/manganese [Mn] alkaline rechargeable batteries (ARBs).

Load parameter identification of wind turbine rotor involving probability and interval variables

ABSTRACT Knowledge of the load parameters of wind turbine rotor is the key problem to eliminate the misalignment of wind turbine. In this paper, an inverse method for identifying the load parameters with imprecise information is investigated by using the probability and interval variables. The interval variables are dealt with interval analysis, only the bounds of the structure response are needed avoiding time-consuming inner loop for structure response prediction. The probability variables are dealt with a proposed iteration method combined micro genetic algorithm with the search interval advance and retreat method. Firstly, at the midpoint of the interval variables, the mean of the load parameters is identified based on the proposed iteration method; secondly, the first-order Taylor expansion is employed to gain the boundary of rotor dynamic response from predicting structure response strip derived from the existence of interval variables; thirdly, the interval of the load parameters is identified via the boundary of rotor dynamic response based on the proposed iteration method. Eventually, the accuracy and efficiency of the proposed inverse method are verified by one numerical example.

Graphene Quantum Dots Pinned on Nanosheets-Assembled NiCo-LDH Hollow Micro-Tunnels: Toward High-Performance Pouch-Type Supercapacitor via the Regulated Electron Localization.

A combined delicate micro-/nano-architecture and corresponding surface modification at the nanometer level can co-tailor the physicochemical properties to realize an advanced supercapacitor electrode material. Herein, nanosheets-assembled nickel-cobalt-layered double hydroxide (NiCo-LDH) hollow micro-tunnels strongly coupled with higher-Fermi-level graphene quantum dots (GQDs) are reported. The unique hollow structure endows the electrolyte accessible to more electroactive sites, while 2D nanosheets have excellent surface chemistry, which favors rapid ion/electron transfer, synergistically resulting in more super-capacitive activities. The experimental and density functional theory calculations recognize that such a precise decoration generally tunes the charge density distribution at the near-surface due to the Fermi-level difference of two components, thus regulating the electron localization, while decorating with conductive GQDs co-improves the charge mobility, affording superior capacitive response and electrode integrity. The as-acquired GQDs@LDH-2 electrode yields excellent capacitance reaching ≈1628 F g-1 at 1 A g-1 and durable cycling longevity (86.2% capacitive retention after 8000 cycles). When coupled with reduced graphene oxide-based negative electrode, the hybrid device unveils an impressive energy/power density (46Wh kg-1 / 7440 W kg-1 ); moreover, a flexible pouch-type supercapacitor can be constructed based on this hybrid system, which holds high mechanical properties and stable energy and power output at various situations, showcasing superb application prospects.

Refractive outcomes of toric intraocular lens in combined trabecular micro bypass stent implantation and cataract surgery in glaucomatous eyes.

To evaluate the impact of trabecular micro bypass stents (iStent Inject) on refractive outcomes with toric intraocular lens (IOL) in glaucomatous eyes. We identified glaucomatous eyes receiving a toric IOL between October 2017 and December 2020. Eyes with iStent implantation were included in the study group and eyes undergoing isolated phacoemulsification served as controls. Corrected and uncorrected visual acuity, manifest refraction, intraocular pressure (IOP), and number of hypotensive drugs three months after surgery were evaluated. 26 eyes comprised the study group and 41 eyes the control group. Mean postoperative refractive cylinder was 0.26D in the control and 0.11D in the iStent group, with 63% and 85% of eyes with a cylinder of 0 and 85% and 92% of eyes with a cylinder ≤ 0.5D respectively. The mean absolute difference between target and outcome spherical equivalent was 0.26D in the control and 0.22D in the iStent group, with all eyes within 0.75D of target. LogMar uncorrected postoperative vision in eyes targeted for emmetropia was 0.04 in the control and 0.03 in the iStent group. There was a statistically significant reduction in IOP and number of hypotensive drugs in both groups, with a mean decrease in IOP of 8.6% in the control and 15.7% in the iStent group. The number of hypotensive drugs dropped from 1.63 ± 0.80 to 1.34 ± 0.91 in the control group and from 2.12 ± 0.65 to 0.44 ± 0.71 in the iStent group. Toric IOLs provide predictable refractive outcomes in glaucomatous eyes undergoing combined phacoemulsification with iStent implantation, reducing postoperative spectacle dependence.

Increasing the Sensitivity of Polymer Optical Fiber Sensing Element in Detecting Humidity: Combination of Macro and Micro Bendings

Humidity sensing is essential in various fields, including industrial processes, agriculture, engineering, and health. A material suitable as a sensing element for humidity detecting is polymer optical fiber (POF). In this study, a combination of micro and macro bendings was proposed to increase the sensitivity of the sensing element. The sensing element was constructed by peeling the out-most coating of the POF, but keeping intact the cladding and core. The macro bending was done upon the peeled part of the POF by making a circular form with varying diameter of 3.5, 4.0 and 4.5 cm. The micro bending was constructed by making a local bent via subjecting to electrical discharge flame from an inductor generator with varying number of micro bendings, i.e., 1, 2 and 3. The sensing element was then tested for its sensitivity as a humidity sensor. The sensing element was positioned inside a self-custom made humidity measurement box consisting of a hygrometer and a pipe to stream water vapor inside the box. The normalized power was measured by varying the % humidity inside the box. In general, the result showed that increasing the humidity caused the normalized lupower to decrease, hence increasing the power loss of the sensing element. Moreover, the sensitivity of the sensing element was increased 10 times for the combined micro and macro bendings compared to a sensing element without micro bendings.
 HIGHLIGHTS
 
 In this study, we increase the sensitivity of a polymer optical fiber (POF) sensing element via a combination of micro and macro bendings. The sensing element is constructed by peeling the out-most coating of the POF, but keeping the cladding and core
 The macro bending is done upon the peeled part of the POF in a circular form. The micro bending is constructed by making a local bent via subjecting to electrical discharge flame from an inductor generator
 The sensing element is then tested for its sensitivity as a humidity sensor. The sensing element is put inside a self-custom made humidity box. The normalized power was measured by varying the % humidity inside the box
 The result shows that increasing the humidity causes the normalized power to decrease, hence increasing the power loss of the sensing element. Moreover, the sensitivity of the sensing element is increased 10 times for the combined micro and macro bendings compared to a sensing element without micro bendings
 
 GRAPHICAL ABSTRACT

Effect of combined micro and nano silicon carbide particles addition on mechanical, wear and moisture absorption features of basalt bidirectional mat/vinyl ester composites

AbstractBasalt fiber reinforcement in polymer composites has recently become very competitive to the routinely used synthetic fiber reinforcements. In the present work, composite specimens were prepared with basalt fiber mat reinforcement in vinyl ester matrix along with varying quantity of the micro and nano silicon carbide (SiC) filler particle ranging from 1 to 5 wt% in combination. Tribological and water absorption properties of the developed hybrid composites were tested to ascertain its potential for commercial applications. The specimen made of SiC particle addictive combination of 3 wt% nano and 3 wt% micro particle exhibited better mechanical characteristics and this mechanical advantage declines beyond 3 wt% SiC filler addition due to agglomeration and poor dispersion of filler particles in the hybrid composite. The microstructural investigation done via scanning electron microscopy reveals the modes of failure, where better pull‐out resistance was displayed by the fiber bonding characteristics with the filler and vinyl ester matrix up to 3 wt% nano and 3 wt% micro SiC filler content. Similarly, the tribological characteristics of the composite specimen for the optimum filler content specimen were superior in comparison with other combinations. Moreover, the water absorption features of the developed hybrid composites were within the acceptable limits for marine and structural applications.

Hardness Penetration Depth Prediction in the Grind-Hardening Process through a Combined FEM model

The grind-hardening process aims to increase the surface hardness of the material through the dual action of the mechanical and thermal load. A novel approach to model the process and predict the hardness penetration depth was developed based exclusively on the prediction of austenite-martensite transformation. A combined micro and macro scale approach was implemented to forecast the temperature reached in the surface starting from the action of a single grain and using its specific cutting power to design a moving heat source representing the interaction between the grinding wheel and the material. The martensitic transformation temperature considered in this paper takes into consideration the fast heat cycle typical of this process. In order to validate the model, tangential surface grinding tests were performed on 42CrMo4 and microstructural analysis with micro-hardness measurements were performed. This research presents a first step in developing a grinding process simulation that includes multi-grain grinding, real grain geometries, binder effect, and real workpiece-grinding wheel kinematics.

An Integrated Approach for Revisiting Basin-Scale Heavy Oil Potential of The Central Sumatera Basin

Central Sumatra Basin is one of the most prolifi c hydrocarbon basins in Indonesia and has proved itself as being the largest contributor to Indonesia’s national crude oil production. Heavy oil fi elds in the basin, such Duri fi eld as the largest one, plays a very important role in making up the basin’s whole oil production output. In general, the Central Sumatra Basin is also acknowledged for its heavy oil potential. Accordingly, a study under the auspices of the Ministry of Energy and Mineral Resources (MEMR) of the Republic of Indonesia is carried out to re-visit the potential. The study establishes and implements an integrated approach formed by a combined macro and micro analyses. In the macro analysis, a combined evaluations of regional geology, geophysics, geochemistry, remote sensing/geographic information system ( GIS), regional geothermal study, and fi eld survey/ microbiology is performed to identify geological positions of the heavy oil potential. In the micro analysis, on the other hand, qualitative and quantitative well-log analyses supported by well-test and laboratory measurement data on the identifi ed geological positions are carried out with an aim of identifying heavy oil bearing reservoirs/traps under three categories of certainty. The main result of the study is identifi cation of 51 fi elds/structures - producing and non-producing – that bears heavy oil within the three categories. Findings of the study can certainly be used as a prerequisite for more intensive and expansive studies to meet the need for a more solid conclusion regarding the heavy oil potential of the Central Sumatra Basin.

Design of combined heat and power micro grid system in plateau area

In order to build a cogeneration microgrid system suitable for the special environment and climate conditions of Tibet Plateau, This paper is mainly through the corresponding generation, transmission and distribution network, to achieve the transmission of electric energy, at the same time reasonable selection of heating equipment and heat dissipation device, under the premise of ensuring the reliability and safety of heating, improve the efficiency of energy utilization, and then achieve the absorption and flexible operation of clean energy (photovoltaic), so as to improve the comfort of the demonstration site.