Modeling of Material Removal Rate for the Fixed-Abrasive Double-Sided Planetary Grinding of a Sapphire Substrate.

Double-sided planetary grinding (DSPG) with a fixed abrasive is widely used in sapphire substrate processing. Compared with conventional free abrasive grinding, it has the advantages of high precision, high efficiency, and environmental protection. In this study, we propose a material removal rate (MRR) model specific to the fixed-abrasive DSPG process for sapphire substrates, grounded in the trajectory length of abrasive particles. In this paper, the material removal rate model is obtained after focusing on the theoretical analysis of the effective number of abrasive grains, the indentation depth of a single abrasive grain, the length of the abrasive grain trajectory, and the groove repetition rate. To validate this model, experiments were conducted on sapphire substrates using a DSPG machine. Theoretical predictions of the material removal rate were then juxtaposed with experimental outcomes across varying grinding pressures and rotational speeds. The trends between theoretical and experimental values showed remarkable consistency, with deviations ranging between 0.2% and 39.2%, thereby substantiating the model's validity. Moreover, leveraging the insights from this model, we optimized the disparity in the material removal rate between two surfaces of the substrate, thereby enhancing the uniformity of the machining process across both surfaces.

Aluminium Nitride Surface Characterization by Grinding with Laser-Ultrasonic Coupling.

Aluminium nitride (AlN) materials are widely used in heat-dissipation substrates and electronic device packages. However, the application of aluminium nitride ceramics is hindered by the obvious anisotropy and high brittleness of its crystals, leading to poor material surface integrity and high grinding force. With the rapid development of microelectronics, the requirements for the material's dimensional accuracy, machining efficiency, and surface accuracy are increasing. Therefore, a new machining process is proposed, combining laser and ultrasonic vibration with grinding. The laser-ultrasonic-assisted grinding (LUAG) of aluminium nitride is simulated by molecular dynamics (MD). Meanwhile, the effects of different processing techniques on grinding force, stress distribution, matrix damage mechanism, and subsurface damage depth are systematically investigated and verified by experiments. The results show that laser-ultrasonic-assisted grinding produces 50% lower grinding forces compared to traditional grinding (TG). The microhardness of AlN can reach more than 1200 HV, and the coefficient of friction and wear is reduced by 42.6%. The dislocation lines of the AlN substrate under this process are short but interlaced, making the material prone to phase transformation. Moreover, the subsurface damage depth is low, realising the substrate's material hardening and wear resistance. These studies not only enhance the comprehension of material build-up and stress damage under the synergistic impact of laser, ultrasonic, and abrasive processing but also indicate that the proposed method can facilitate and realise high-performance machining of aluminium nitride substrate surfaces.

Study of Prefabricated Crack Propagation on Monocrystalline Silicon Surfaces for Grinding Damage Analysis.

Crack generation and propagation are critical aspects of grinding processes for hard and brittle materials. Despite extensive research, the impact of residual cracks from coarse grinding on the cracks generated during fine grinding remains unexplored. This study aims to bridge this gap by examining the propagation law of existing cracks under indentation using the extended finite element method. The results reveal that prefabricated cracks with depths less than the crack depth produced on an undamaged surface tend to extend further without surpassing the latter. Conversely, deeper prefabricated cracks do not exhibit significant expansion. A novel method combining indentation and prefabricated cracks with fracture strength tests is proposed to determine crack propagation. Silicon wafers with varying damaged surfaces are analyzed, and changes in fracture strength, measured by the ball-on-ring method, are utilized to determine crack propagation. The experimental results confirm the proposed crack evolution law, validated by damage assessments across different grinding processes, which is suitable for crack damage. The findings demonstrate that residual cracks from coarse grinding are negligible in predicting the maximum crack depth during fine grinding. This research provides a crucial foundation for optimizing the wafer thinning process in 3D stacked chip manufacturing, establishing that changes in fracture strength are a reliable indicator of crack propagation feasibility.

Synthesis and Anticancer Evaluation of Disubstituted Benzimidazoles via One-Pot Telescopic Grinding Approach.

Benzimidazole compounds are known for their broad spectrum therapeutic potentials. A small library of benzimidazole derivatives were designed and synthesized via a one-pot telescopic grinding approach. The ability of these molecules as proposed anticancer agents were evaluated by their potential to bind to two important cancer pathway protein targets, human estrogen receptors and cyclin dependant kinases, 3ERT and 5FGK respectively. Further nucleic acid binding and reactive oxygen species (ROS) scavenging capacity being in the scope for anticancer potential evaluations, the ability of these molecules have been evaluated for the same. Further, to support the experimental and computational results, AI-assisted tools were employed to predict the anticancer activity (PASS) as well as to identify false positives (PAINS). Also, the druggability of the proposed compounds was evaluated by following their pharmacokinetic parameters - ADME.

Role of superfine grinding in whole-purple-wheat flour. Part II: Impacts of size reduction on dough properties, bread quality and in vitro starch digestion.

This study aimed to enhance bread functionality while maintaining its organoleptic attributes by employing superfine grinding and purple wheat, through characterizing dough properties, bread quality attributes, and in vitro starch digestibility. Compared with dough made from commercial-superfine-whole-wheat flour, the superfine-whole-purple-wheat dough was less strong, comparably extensible, and higher in gassing power during mixing, moulding and proofing, respectively. The subsequent bread quality analysis of crumb grain features and texture indicated that the bread made from superfine-whole-purple-wheat flour was more porous and softer with a larger specific volume (3.21 ± 0.20 cm3/g) than that made from commercial-superfine-whole-wheat flour (2.30 ± 0.17 cm3/g). Additionally, the superfine-whole-purple-wheat bread had a significantly slower glucose release (k = 0.0048 min-1) during in vitro starch digestion as compared to the superfine-whole-wheat bread (k = 0.0065 min-1). Therefore, this study demonstrates that using superfine-whole-purple-wheat flour leads to bread with desirable quality attributes and potential health benefits compared to conventional whole-wheat flour.

Engineering properties as a supplement cementitious material of ground copper reduction slag extracted valuable metal from Cu slag.

We have examined whether the copper reduction slag (CRS) generated after recovering valuable metals from copper slag (CS) by reduction process can be used as supplementary cementitious materials (SCMs). According to the test results, the Cu secondary slag with low Fe, Cu, and heavy metal contents had a suitable oxide composition for using as a SCM. CRS showed better grinding efficiency than that of ground blast furnace slag (GGBS). Ground CRS contributed to the formation of tobermorite under autoclaved curing conditions. The compressive strength of CRS mortar replacing 50 % of OPC generated 93 % of that of the OPC mortar. Based on the results of this study, we found that the CRS has highly appropriate engineering characteristics for using as SCMs for concrete. In addition, it is judged that the method of using secondary slag as a material for precast concrete produced under hydrothermal conditions can greatly contribute to the construction process of buildings by securing mechanical performance.

A pathway for detection of gastric cancer biomarkers via using a layer-by-layer coated D-shaped grinding long-period fiber grating sensor.

Gastric cancer significantly contributes to global cancer mortality, often leading to inoperable stages and high recurrence rates post-surgery. Elevated levels of G-17 and G-gly have been identified as potential risk factors, particularly in patients with duodenal ulcers. This study introduces an innovative D-shaped grinding long-period fiber grating sensor (D-LLPFGs) designed for non-invasive detection of the gastrin G-17 antigen, employing a layer-by-layer chemical self-assembly to bond G-17 antibodies onto the fiber surface through hydrogen bonding. The D-LLPFGs sensor demonstrated significant spectral shifts within 1 min of antigen-antibody interaction, highlighting its rapid detection capability. At an optimized antibody concentration of 4 µg/ml, antigen testing across different concentrations (10, 12.5, 20, 50 µg/ml) showed peak changes at 12.5 µg/ml antigen, with a 1.186 nm shift and 0.503 dB loss. The sensor exhibited a wavelength sensitivity of 0.095 nm/µg/ml, indicating its high sensitivity and potential in gastric cancer classification, diagnosis, and treatment. This research concludes that the D-shaped fiber sensor is an effective and sensitive tool for detecting G-17 antigen levels, presenting a significant advancement in non-invasive gastric cancer diagnosis. Its quick response time and high sensitivity highlight its potential for broad biomedical applications, offering a new avenue for early cancer detection and improving patient prognosis. The success of this study opens the door to further exploration and implementation of fiber optic sensors in clinical settings, marking a significant step forward in the fight against gastric cancer.

Multi-component forms of the 2nd generation H1 receptor antagonist drug, Bilastine and its enhanced physicochemical characteristics.

Bilastine (BIL) is a novel 2nd generation antihistamine medication is used to treat symptoms of chronic urticaria and allergic rhinitis. However, its poor solubility limits its therapeutic efficacy. In order to enhance the physicochemical characteristics of BIL, various molecular adducts of BIL (Salt, hydrate and co-crystal) were discovered in this study using two distinct salt-formers: Terephthalic acid (TA), 2,4-Dihydroxybenzoic acid (2,4-DHBA), and three nutraceuticals (Vanillic Acid (VA), Hydroquinone (HQN) and Hippuric acid (HA)). Various analytical methods were used to examine the synthesised adducts, including Powder X-Ray Diffraction (PXRD), Single Crystal X-ray Diffraction (SCXRD), and thermal analysis (Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC)). Single-crystal X-ray diffraction (SCXRD) studies avowed that the architectures of the molecular adducts are maintained in the solid state by an array of strong (N+H⋯O-, NH⋯O, OH⋯O) and weak (CH⋯O) hydrogen bonds. Additionally, a solubility test was performed to establish the in vitro release characteristics of newly synthesised BIL adducts and it observed that most of the molecular adducts exhibit higher rates of dissolution in comparison to pure BIL; in particular, BIL.TA.HYD showed the highest solubility and the fastest rate of dissolution. Moreover, experiments on flux permeability and diffusion demonstrated that the BIL.TA.HYD and BIL.VA salts had strong permeability and a high diffusion rate. In addition, the synthesized adduct's stability was assessed at 25 °C and 90 % ± 5 % relative humidity, and it was found that all the molecular salts were stable and did not undergo any phase changes or dissociation. The foregoing result leads us to believe that the newly synthesized molecular adducts' increased permeability and solubility will be advantageous for the creation of novel BIL formulations.

Effect of ultrafine grinding on the structure and physical properties of pregelatinized rice starch.

This study used a combination method of ultrafine grinding and pregelatinization to modify rice starch (RS) to delay its retrogradation and provide a rationale for prolonging rice product shelf life. The structure and physicochemical properties of the pregelatinized ultrafine grinding rice starch (PURS) were compared with those of RS, ultrafine grinding rice starch (URS), and pregelatinized rice starch (PRS). The microstructure, molecular weight, branched starch length distribution, short-range order, crystal structure, and physical properties of RS, URS, PRS, and PURS were analyzed, respectively. Results showed that RS, URS, PRS, and PURS granules exhibited similar spherical or polygonal shapes, and the content of amylose and short-branched starch in PURS increased compared with RS, URS, and PRS. Furthermore, the cross-polarization of PRS and PURS disappeared. Long-chain amylopectin and average molecular weight of PURS decreased significantly after ultrafine grinding. Our study suggested reduced breakdown value and setback value and improved gel stability, and PURS was beneficial for delaying retrogradation compared to RS, URS, and PRS. The ultrafine grinding method improved the water swelling capacity (WSC), solubility, pasting properties, and gelation properties of PRS. The hardness of PURS was reduced by ultrafine grinding. These suggest that the combination of ultrafine grinding and pregelatinization could improve the properties of RS. Pearson's correlation analysis showed that the structure of PURS significantly influenced the physicochemical properties. The present study was helpful in better understanding the importance of ultrafine grinding in improving the anti-retrogradation of PURS and provided new insights into extending the shelf life of rice products by ultrafine grinding and pregelatinization.

A Comparative Evaluation of Powder Characteristics of Recycled Material from Bronze Grinding Chips for Additive Manufacturing.

In the manufacturing process of ship propellers, large quantities of grinding chips are generated. These grinding chips result from the finishing of the blade surfaces after the primary casting process of the propeller. The aim of this study was to investigate and compare different preparation processes used to produce chip powders with sufficient powder quality for the additive manufacturing process of directed energy deposition. The preparation of the samples was performed through different sieving, milling and re-melting processes. For the characterization of the prepared samples, powder analysis according to relevant industry standards was carried out. It was found that the re-melting processes result in superior powder quality for additive manufacturing in terms of particle size, morphology, and flowability. For some characteristics, the powder exhibits even better properties than those of commercial powders. Furthermore, the powder properties of the milled samples demonstrate a promising potential for use in additive manufacturing.

Multi-Step Two-Dimensional Ultrasonic-Assisted Grinding of Silicon Carbide: An Experimental Study on Surface Topography and Roughness.

Two-dimensional ultrasonic-assisted grinding (2D-UAG) has exhibited advantages in improving the machining quality of hard and brittle materials. However, the grinding mechanism in this process has not been thoroughly revealed due to the complicated material removal behaviors. In this study, multi-step 2D-UAG experiments of silicon carbide are conducted to investigate the effects of machining parameters on surface quality. The experimental results demonstrate that the tool amplitude and the workpiece amplitude have similar effects on surface roughness. In the rough grinding stage, the surface roughness decreases continuously with increasing ultrasonic amplitudes and the material is mainly removed by brittle fracture with different surface defects. Under semi-finishing and finishing grinding steps, the surface roughness first declines and then increases as the tool amplitude or workpiece amplitude grows from 0 µm to 8 µm and the inflection point appears around 4 µm. The surface damage contains small-sized pits with band-like distribution and localized grooves. Furthermore, the influences of cutting parameters on surface quality are similar to those in conventional grinding. Discussions of the underlying mechanisms for the experimental phenomena are also provided based on kinematic analysis. The conclusions gained in this study can provide references for the optimization of machining parameters in 2D-UAG of hard and brittle materials.

Microwave absorber utilization to improve grinding and particle surface structure characteristics of torrefied switchgrass particles for bioenergy applications.

Torrefaction treatment improves biomass grindability by transforming the fibrous herbaceous to a more brittle and lighter coal-like material. Microwave-assisted torrefaction is a promising technology for biomass conversion into energy, fuels, and chemicals. The study applied microwave absorbers in the torrefaction process to improve the thermochemical characteristics and grindability of switchgrass. Switchgrass in two particle sizes was torrefied in a microwave reactor with biochar added as a microwave absorber under inert conditions. After torrefaction, the geometric mean particle and size distribution and selected physical characteristics were evaluated, and the grindability of the torrefied ground and chopped with and without biochar were compared with those of untreated switchgrass. The geometric diameter results decreased, and the specific energy required for grinding torrefied switchgrass with biochar was significantly reduced with extended residence times and at a torrefaction temperature of 300 °C. After grinding, the lowest grinding energy of 32.82 kJ at 300 °C/20 min was recorded with torrefied ground switchgrass/biochar. The 10% biochar added/250 °C resulted in deep cell wall disarrangement, whereas at a torrefaction temperature of 300 °C, large surface deformation and carbonized weight fractions were observed.

Impact of particle size of cereals and soyabean meal on the intestinal development of weanling pigs and growth performance after an enteric challenge with F4-positive enterotoxigenic E. coli.

The objectives were to determine the interactive effect of particle size of soyabean meal (SBM) and whole wheat, barley and wheat bran (CER) on growth performance of weanling pigs after an enterotoxigenic Escherichia coli F4 challenge (Experiment 1) and on gastrointestinal (GIT) development immediately after weaning (Experiment 2). Experiment 1 consisted of 192 pigs (24 ± 3 days of age; 7.4 ± 1.1 kg weaning bodyweight [BW]) selected for Escherichia coli (E. coli) F4 susceptibility. Pigs were given an oral E. coli inoculum at postweaning day 7, to induce an enteric health challenge. Experiment 2 consisted of 40 pigs (24 ± 3 days of age; 7.2 ± 1.0 kg weaning BW) that were killed on postweaning day 8 or 9, to determine the effects of particle size on GIT development and functionality. Four experimental diets were used in a 2 × 2 factorial design: (1) coarse CER and coarse SBM, (2) coarse CER and fine SBM (CERcSBMf), (3) fine CER and coarse SBM, or (4) fine CER and fine SBM (CERfSBMf). Results showed no interaction between SBM and CER coarseness on growth performance, GIT development and functionality. Diarrhoea incidence was higher (p < 0.05) for CERfSBMf during the 2 weeks following the E. coli challenge compared to the other diets. Daily gain and feed intake during this period were higher (p < 0.05) for pigs fed CERc compared to CERf. Empty stomach weight tended to be greater by 8% (p = 0.09) for CERc compared to CERf. Gastric protein (p = 0.05) and starch (p = 0.04) disappearances were greater for SBMf compared to SBMc. Thus, CERcSBMf resulted in the best growth performance and lowest diarrhoea incidence during the 2 weeks following the E. coli challenge, which may be explained by changes in stomach functionality but not by changes in other parts of the GIT.

Food Grinding Behavior: A Review of Causality and Influential Factors.

Food waste is a common issue arising from grinding of food by experimental animals, leading to excessive food scraps falling into cages. In the wild, animals grind food by gnawing vegetation and seeds, potentially damaging the ecological environment. However, limited ecology studies have focused on food grinding behavior since the last century, with even fewer on rodent food grinding, particularly recently. Although food grinding's function is partially understood, its biological purposes remain under-investigated and driving factors unclear. This review aims to explain potential causes of animal food grinding, identify influencing factors, and discuss contexts and limitations. Specifically, we emphasize recent progress on gut microbiota significance for food grinding. Moreover, we show abnormal food grinding is determined by degree of excess normal behavior, emphasizing food grinding is not meaningless. Findings from this review promote comprehensive research on the myriad factors, multifaceted roles, and intricate evolution underlying food grinding behavior, benefiting laboratory animal husbandry and ecological environment protection, and identifying potential physiological benefits yet undiscovered.

Cement pastes containing air entraining agent release the biocide octylisothiazolinone posing ecotoxicological effects.

We investigated whether cement pastes are a possible source of ecotoxicologically potent substances. For this purpose, leaching according to DIN EN 16637-2 was performed on portland cement pastes as well as blast furnace slag cement with and without an air entraining agent (AEA). The AEA, consisting of wood rosin and resin, contained the stabiliser drometrizole and the biocide octylisothiazolinone (OIT), which was confirmed by our non-target screening (NTS). Our ecotoxicological studies (Daphnia magna, Aliivibrio fischeri and Desmodesmus subspicatus) of the pure cement eluates showed no effects at all. In these samples, it was possible to attribute up to 85 % of the dissolved organic carbon (DOC) to acetate, formate and diethylene glycol (DiEG). Eluates from cement pastes with AEA contained up to 70 µg/L octylisothiazolinone (OIT), and no drometrizole was found. Around 90 % of the total OIT release happened within the first 6 h. It was possible to attribute the observed ecotoxicological effects mainly to the OIT concentrations. Additional leaching with elevated sulphate concentrations (800 mg/L) did not influence the release of DOC and OIT or increase the ecotoxicological effects. As a consequence, we advise curing the cement paste for 24 h prior to use, as this largely avoids the release of OIT and the observed ecotoxicological effects.

Influence mechanism of grinding surface quality of 20CrMnTi steel on contact failure.

To reveal the influence mechanism of the grinding surface quality of 20CrMnTi steel components on the tribological characteristics and contact fatigue performance, accelerated tests for sliding friction wear and fatigue damage were carried out. Tribological characteristics and contact fatigue performance get worse with increasing surface roughness while getting better with increasing surface microhardness. Residual compressive stress is conducive to inhibiting the initiation and propagation of cracks and promoting contact fatigue performance. Additionally, mechanical friction, abrasive wear, adhesive wear and fatigue damage coexist and form a competing failure mechanism under the synergistic effect of frictional wear and contact fatigue failure. The damage process mainly manifests as wear, stress concentration induced fatigue, microcracks, pitting, and spalling in the shallow layer. This study is more beneficial to promote the 20CrMnTi steel transmission parts manufacturing products for high precision, low damage, and long life.

Material Removal Mechanism of SiC Ceramic by Porous Diamond Grinding Wheel Using Discrete Element Simulation.

SiC ceramics are typically hard and brittle materials. Serious surface/subsurface damage occurs during the grinding process due to the poor self-sharpening ability of monocrystalline diamond grits. Nevertheless, recent findings have demonstrated that porous diamond grits can achieve high-efficiency and low-damage machining. However, research on the removal mechanism of porous diamond grit while grinding SiC ceramic materials is still in the bottleneck stage. A discrete element simulation model of the porous diamond grit while grinding SiC ceramics was established to optimize the grinding parameters (e.g., grinding wheel speed, undeformed chip thickness) and pore parameters (e.g., cutting edge density) of the porous diamond grit. The influence of these above parameters on the removal and damage of SiC ceramics was explored from a microscopic perspective, comparing with monocrystalline diamond grit. The results show that porous diamond grits cause less damage to SiC ceramics and have better grinding performance than monocrystalline diamond grits. In addition, the optimal cutting edge density and undeformed chip thickness should be controlled at 1-3 and 1-2 um, respectively, and the grinding wheel speed should be greater than 80 m/s. The research results lay a scientific foundation for the efficient and low-damage grinding of hard and brittle materials represented by SiC ceramics, exhibiting theoretical significance and practical value.

Constant force grinding controller for robots based on SAC optimal parameter finding algorithm.

Since conventional PID (Proportional-Integral-Derivative) controllers hardly control the robot to stabilize for constant force grinding under changing environmental conditions, it is necessary to add a compensation term to conventional PID controllers. An optimal parameter finding algorithm based on SAC (Soft-Actor-Critic) is proposed to solve the problem that the compensation term parameters are difficult to obtain, including training state action and normalization preprocessing, reward function design, and targeted deep neural network design. The algorithm is used to find the optimal controller compensation term parameters and applied to the PID controller to complete the compensation through the inverse kinematics of the robot to achieve constant force grinding control. To verify the algorithm's feasibility, a simulation model of a grinding robot with sensible force information is established, and the simulation results show that the controller trained with the algorithm can achieve constant force grinding of the robot. Finally, the robot constant force grinding experimental system platform is built for testing, which verifies the control effect of the optimal parameter finding algorithm on the robot constant force grinding and has specific environmental adaptability.

A Three-Dimensional Assessment of a Type I Shallow Palatogingival Groove by Cone Beam Computed Tomography: A Case Report.

The palatogingival groove is a developmental anomaly on the palatal surface of the maxillary anterior teeth. The shallow groove, often less than 1 mm, is challenging to diagnose, particularly in radiographic examinations. Such grooves are mistaken for root fractures. In this case study, we explore the prevalence, types, radiological appearances, and treatment options of type I shallow palatogingival grooves encountered in cone beam computed tomography.

Comprehension of drying kinetics and stone milling process of chestnuts: a focus on moisture content, milling speed, and energy evaluation.

BACKGROUND: Chestnut flour plays an important role in the production of bread, bakery products, and gluten-free foods. Most of the references in the literature focus on the drying process itself and not on the effects of the drying and milling processes. Moreover, the literature is lacking recommendations regarding optimal moisture content and milling speed, thus motivating the present study. The first aim is to understand the chestnut drying process through an in-depth evaluation of drying kinetics; the second aim is to assess the effects of three different moisture content (2%, 4% and 6%) and three different stone rotational speeds (120, 220 and 320 rpm) on operative milling parameters (flour yield, milling time, energy consumption, temperature increase, average power, specific milling energy), flour particle size distribution, and chestnut flours characteristics. RESULTS: The results show that moisture content and stone rotational speed have statistically-significant effects on milling operative parameters, flour particle size and chestnut flour composition. In particular, stone rotational speed affected almost all the tested variables (mill operative parameters, flour particle size distribution, and flour characteristics). Therefore, as the stone rotational speed increases, energy consumption, average power, specific energy, and damaged starch content significantly increase. CONCLUSION: These findings clearly show that moisture content and stone rotational speed are powerful tools that allow the exploiation of the milling process to modulate the characteristics of the obtained flours. In conclusion, two different approaches for chestnut milling were suggested depending on the type of flour to be produced. © 2024 Society of Chemical Industry.