Large Holes Research Articles

Effect of thermoplastic mask hole diameter on dose distribution in the build-up region of medical LINAC

This study aims to investigate the effect of variations in the hole diameter of unstretched thermoplastic masks offered by a single company on the dose distribution in the build-up region. 2, 2.5, 3 and 4 mm hole diameters masks with the same properties were irradiated with 6 MV X-rays and dose distribution was analyzed according to the open field. Dose measurements were obtained with a parallel plane ionization chamber. All irradiations were repeated for 5 × 5, 8 × 8, 10 × 10 and 15 × 15 cm2 beam fields. It was observed that the mask had a bolus effect in all measurements. It was observed that this bolus effect varied especially depending on the hole diameter in the mask. In a 10 × 10 cm2 field, the dmax depth without mask was 15 mm, while the dmax for masks with 2, 2.5, 3 and 4 mm hole diameters was 11, 12, 13 and 13 mm, respectively. It was observed that the mask hole diameter affected the dmax depth. Thermoplastic masks with large hole diameters increase the surface dose less than those with small hole diameters.

Comparison of the use of internal limiting membrane flaps versus conventional ILM peeling on post-operative anatomical and visual outcomes in large macular holes

BackgroundIdiopathic full-thickness macular hole (iFTMH) closure rates following conventional vitrectomy, gas tamponade and internal limiting membrane (ILM) peeling decrease when the minimum linear diameter (MLD) ≥ 500 microns. ILM flap creation has been proposed to improve closure in larger holes. This study evaluated the anatomical and functional impact of ILM flap introduction to routine practice in iFTMH ≥500 microns.MethodsRetrospective, interventional analysis of prospectively collected data of 191 eyes from consecutive surgeries for primary iFTMH ≥500 microns performed by two surgeons between June 2018 and June 2022, during which both surgeons replaced ILM peeling with ILM flap creation. Post-operative best-corrected visual acuity (BCVA) and anatomical closure were compared between Group 1 (ILM peel) and Group 2 (ILM flap) in an intention-to-treat analysis.ResultsRates of iFTMH closure were greater in the ILM flap group (77/80; 96.3%) than the ILM peel group (94/110; 85.5%) (OR = 4.37, 95% CI = 1.23–15.55, p = 0.023). A non-significant increase in post-operative BCVA improvement was observed in the ILM flap group (p = 0.084). There was no statistically significant difference in final BCVA (p = 0.83). Multivariate logistic regression found only MLD (OR = 0.993, 95% CI = 0.989–0.997, p = 0.001) and ILM flap group (OR = 5.795, 95% CI = 1.313–25.570, p = 0.020) predicted primary closure.ConclusionILM flap creation improves closure rates in larger holes and should be considered routinely in iFTMH ≥500 microns. Whether ILM flaps affect post-operative visual function remains uncertain.

Off target of distal interlocking screw in short cephalomedullary nail fixation for intertrochanteric femur fractures

To analyze the causes and treatment of off target of the distal interlocking screws when short cephalomeduallry nails were installed through jig-guided targeting device, and to put forward the technical points to prevent off target. Retrospective analysis of 9 patients with intertrochanteric fractures treated between July 2014 and June 2023 was conducted, in which off target occurred during the insertion of the distal interlocking screw by jig-guided targeting device in short cephalomedullary nailling (<24 cm). There were 1 male and 8 females, with an average age of 82.7 years (range, 73-94 years). There were 3 cases of type A1, 5 cases of type A2, and 1 case of type A3 according to 2018-AO/Orthopaedic Trauma Association (AO/OTA) fracture classification. As for the misaligned distal interlocking screw, six parameters were collected and analyzed, including the time of finding, the position, the type of passing through the cortical bone, the special circumstances during operation (such as the need to remove the intramedullary nail for reaming the diaphysis, hammering, etc.), the treatment, and the patient follow-up results. In the 9 patients, the off target of the distal interlocking screw was found in 7 cases during operation and in 2 cases after operation; the locking screw was located behind the nail in 7 cases and in front of the nail in 2 cases; the off target locking screw was passing tangentially in transcortical patern in 6 cases and in bicortical pattern through the medullary cavity in 3 cases. Three cases were attributed to the mismatch between the nail and the femur, two of which were attributed to the narrow femoral medullary cavity, one of which was attributed to the large anterolateral femoral bowing, and the other 6 cases were attributed to technical errors such as the loosening of the jig-guided targeting device, the tension of the fascia lata, and the blunt of the drill. In the 7 cases found during operation, the misaligned interlocking screw was removed first and the screw hole was left vacant, then in 2 cases, the interlocking screw was not used further; in 1 case, the distal dynamic hole was successfully inserted with a dynamic guide frame, and in 4 cases, the interlocking screw was successfully put after 2-3 attempts, leaving a large hole in the lateral cortex. No special treatment was performed in 2 cases found after operation. One patient was out of bed early after operation, 7 patients were in bed for 1 month, and 1 patient deteriorated to A3 type after operation and was in bed for 3 months. All the 9 patients were followed up 6-12 months, with an average of 8 months. Fracture healing was achieved in 8 patients. One patient with vacant interlocking screw had a secondary spiral fracture of the femoral shaft 3 months later, and was refixed with a long cephalomedullary nail and circlage wiring. Distal interlocking screw off target is rare, but when it occurs, it leaves a large cortical hole in the osteoporotic femoral shaft, reducing bone strength; the use of precision instruments and attention to technical details can reduce this adverse phenomenon.

Surface modification of ZrC dispersion-strengthened W under low energy He plasma irradiation

ZrC dispersion-strengthened W exhibits high strength/ductility, low ductile-to-brittle transition temperature, and excellent thermal shock resistance, making it a promising candidate plasma-facing material for future fusion devices. In this study, surface modification of 0.5 wt.% ZrC dispersion-strengthened W (WZrC) under low energy and high fluence He plasma irradiation at high temperature was presented. Under the energy of 90 eV and fluence ranging from 6 × 1024 He·m−2–2 × 1026 He·m−2 He irradiation at 920 °C, a typical fuzz nanostructure appeared on the W matrix of WZrC. The thickness of fuzz layer is proportional to the square root of He irradiation fluence. The fuzz showed comparable thickness and structural features to pure W, indicating limited effects of the particle’s addition on resistance to high fluence He irradiation at high temperatures. Under continuous He injection, the fuzz would grow extending onto the particle area, making the particle obscured. Besides, the erosion behavior of particles under He plasma irradiation has been investigated, which is thought to be dominated by a sputtering process. Under the He influence of 6 × 1024 He·m−2, only nanopores were observed in the surface region. With fluence increasing to 5 × 1025 He·m−2, the surface became relatively uneven with larger holes. W aggregated in spots and distributed on the surface of the particle, which might be the result of subthreshold sputtering and deposition. When fluence further increased to 2 × 1026 He·m−2, the particles were eroded completely and covered by the extended fuzz, forming cavities. In addition, distinctive layered nanotendrils were observed above the cavities, which were characterized to consist of inner W-riched skeletons and outer Zr-riched layers. It indicates that the layered nanotendrils should be the result of fuzz extension combined with particle sputtering/deposition.

Revitalizing Degraded and Abandoned Lands: Reflections from Local Government Involvement in Mud Brick Production - Tanzania

The study assessed local government involvement in revitalising abandoned holes and degraded lands around brick-making sites in Morogoro Municipality. Specifically, it delineated the effects of mudbrick-making activities on the communities surrounding the brick-making sites, identified alternative uses of the abandoned holes in the brick-making sites, and established the knowledge required by the community and brick-makers for improving abandoned land use for sustainability. Several techniques were utilised in data collection, including interviews and focus group discussions with village and ward leaders, district environmental officers, district community development officers, district planners, mud brick makers, and some members of the community from three specific wards, namely Kauzeni, Mindu, and Kihonda Maghorofani. The findings revealed a significant contribution of the mudbrick-making industry to enhancing income and improving the living standards of communities through employment creation. Particularly, women were involved in selling food to brick makers, while youth actively participated in brick-making activities. The abandoned holes resulting from soil extraction were repurposed for fishing, vegetable cultivation, and sugar cane production. The income accrued from these activities improved housing standards and increased social interaction among people from different regions, including seasonal migrants attracted to brick-making activities. Despite the noted positive effects, mud brick activities contributed significantly to land degradation due to the traditional technologies used in the process, resulting in large holes that posed risks to human and livestock lives. The study recommends enhancing brick makers' and landowners' awareness of implementing mud brick-making activities with appropriate sustainable environmental protection to improve the socio-economic status of both brick makers and the broader community.

Outcomes of inverted internal limiting membrane flap surgery for chronic large macular holes in a sub-Saharan African setting

TopicOutcomes of inverted internal limiting membrane (ILM) flap surgery for chronic large macular holes (MH) in a sub-Saharan Africa setting. PurposeTo report the anatomic and visual outcomes of ILM flap surgery without face-down positioning for eyes with chronic large MH at Eye Foundation Hospital, Lagos, Nigeria. DesignRetrospective, observational study. MethodsCase files of patients who underwent inverted ILM flap surgery for large MH in the retina unit of the Eye Foundation Hospital, Lagos, Nigeria, between January 2022 and December 2022 were reviewed. ResultsThe study included 30 eyes of 29 patients. MH size was between 471 μm and 1530 μm. The mean overall preoperative best corrected logMAR visual acuity was 1.27 ± 0.58. A one-line worsening of preoperative logMAR vision was associated with an increase in MH size by 129.5 μm (p = 0.056). MH closure was achieved in 90% of eyes. There was an improvement in mean best corrected postoperative logMAR visual acuity at 6 months to 0.83 ± 0.49 (p < 0.001). Good visual outcomes were seen in 60.7% of eyes. The remodeling of the external limiting membrane seen in 46.7% of eyes was associated with good visual outcomes (p = 0.04). ConclusionThere was a 90% anatomic closure rate for chronic large MHs that underwent inverted internal limiting membrane flap surgery among our series of patients in a sub-Saharan African setting. Good visual outcomes were seen in 60.7% of eyes, with an overall improvement in logMAR visual acuity.

Research on a kind of positioning anti-eccentric fixture for measuring thin wall gear with special big inner hole

This paper mainly studies and designs the clamping tool which is installed in the measuring of big gears with big inner holes and thin walls. This paper analyzes the disadvantages of conventional clamping of large gears with special inner holes, and presents an example of the research and development of the Assembly of the mounting and positioning device of the special large inner hole gear based on the gear measuring instrument. At present, in the field of gear measurement, the measurement of large gears is always a technical problem. The technical ability of gear testing in our country is restricted by various factors. Most gear high-precision instruments and their accessories still depend on imports, which cannot be a good solution to the measurement of special gear installation and positioning problems from the economy and timeliness. Especially, large gears with large bores and thin walls face the problem of determining the position of the measuring device and the measured gears, that is, the measuring datum is difficult to determine [1]. This paper proposes how to use the existing gear measuring instrument to develop and use small accessories, so as to help the production enterprises and measuring institutions solve the problem of reference positioning in the actual production measurement process and determine the accuracy of special gear samples.

Diamond for High-Power, High-Frequency, and Terahertz Plasma Wave Electronics.

High thermal conductivity and a high breakdown field make diamond a promising candidate for high-power and high-temperature semiconductor devices. Diamond also has a higher radiation hardness than silicon. Recent studies show that diamond has exceptionally large electron and hole momentum relaxation times, facilitating compact THz and sub-THz plasmonic sources and detectors working at room temperature and elevated temperatures. The plasmonic resonance quality factor in diamond TeraFETs could be larger than unity for the 240-600 GHz atmospheric window, which could make them viable for 6G communications applications. This paper reviews the potential and challenges of diamond technology, showing that diamond might augment silicon for high-power and high-frequency compact devices with special advantages for extreme environments and high-frequency applications.

Organic inorganic hybrid solar cell with photoactive hole transporting CuSbS2 nanoflakes

An easy-to-process, low-cost and environmentally benign organic inorganic hybrid solar cell (HSC) based on textured silicon (t-Si) is fabricated. The heterojunction solid state cell is composed of n-type t-Si having a micro-pyramidal surface with good anti-reflection properties, coated with a p-type layer of CuSbS2 nanoflakes dispersed in a polymer matrix of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The large hole density (2.7 × 1015 /cm3), high photoconductivity (5.37 mS cm−1), mono-dispersity of nanoflakes (50–80 nm), increased recombination resistance and a broad band absorption, with a band gap of ∼ 0.85 eV render CuSbS2 nanoflakes to be an ideal photo-absorber cum hole transport material for a highly scalable all solid-state HSC. Besides these attributes, the thermodynamically aligned energy levels of t-Si and CuSbS2 nanoflakes enable one-directional pathways for transfer and transport of electrons and holes to their respective contacts, yielding a high-power conversion efficiency (PCE) of 8.5 % under AM 1.5, 1 sun irradiance along with an average external quantum efficiency of 60 % superior by 39.2 % relative to its analogue devoid of CuSbS2. The effect of alkali texturization on the photovoltaic performance of the cells is also delineated by comparison with planar (pl)-Si based cells. The long-term stability of the In-Ga/t-Si/PEDOT:PSS + CuSbS2/Ag cell under intermittent illumination and storage over eight weeks confirmed from the nominal drop in PCE by ∼ 22 % demonstrates the efficacy of this affordable wet-chemistry approach for developing robust Si based HSC contrasting with the classical and expensive inorganic p-n junction crystalline Si solar cell.

Large invertebrate decomposers contribute to faster leaf litter decomposition in Fraxinus excelsior-dominated habitats: Implications of ash dieback

Leaf litter decomposition is a major component of nutrient cycling which depends on the quality and quantity of the leaf material. Ash trees (Fraxinus excelsior, decay time ∼ 0.4 years) are declining throughout Europe due to a fungal pathogen (Hymenoscyphus fraxineus), which is likely to alter biochemical cycling across the continent. The ecological impact of losing species with fast decomposing leaves is not well quantified. In this study we examine how decomposition of three leaf species with varying decomposition rates including ash, sycamore (Acer pseudoplatanus, decay time ∼ 1.4 years), and beech (Fagus sylvatica, decay time ∼ 6.8 years) differ in habitats with and without ash as the dominant overstorey species. Ten plots (40 m × 40 m) were set up in five locations representing ash dominated and non-ash dominated habitats. In each plot mesh bags (30 cm × 30 cm, 0.5 mm aperture) with a single leaf species (5 g) were used to include (large holes added) and exclude macrofauna invertebrates (with a focus on decomposer organisms such as earthworms, millipedes, and woodlice). The mesh bags were installed in October 2020 and retrieved without replacement at exponential intervals after 6, 12, 24 and 48 weeks. Total leaf mass loss was highest in the ash dominated habitat (ash dominated: 88.5%, non-ash dominated: 66.5%) where macrofauna were the main contributor (macrofauna: 96%, microorganisms/mesofauna: 4%). The difference between macrofauna vs microorganisms and mesofauna was less pronounced in the non-ash dominated habitat (macrofauna: 68%, microorganisms/mesofauna: 31%). Our results suggest that if ash dominated habitats are replaced by species such as sycamore, beech, and oak, the role of macrofauna decomposers will be reduced and leaf litter decomposition rates will decrease by 25%. These results provide important insights for future ash dieback management decisions.

Structures, physical properties and antibacterial activity of silver nanoparticles of Lactiplantibacillus plantarum exopolysaccharide

Lactic acid bacteria (LAB) exopolysaccharide (EPS) has good water absorption, high viscosity, good stability, so it was widely used in probiotics fields. In this study, EPS-producing LAB strain Lactiplantibacillus plantarum HDL-03 was isolated and identified. Moreover, the HDL-03 EPS was used as a stabilizer and mixed with AgNO3 to synthesize a novel nanoparticle AgNPs whose structure and properties were explored. The monosaccharide composition and molecular weight indicated that HDL-03 EPS was a heteropolysaccharide composed of mannose and glucose. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy analysis and methylation results jointly proved it was a heteropolysaccharide containing 1,3-Manp and 1,6-Glcp. The X-Ray diffraction (XRD) results showed that this EPS has an amorphous structure, while the synthesized AgNPs have crystalline properties. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicated EPS had a smooth and dense sheet structure, while the surface of AgNPs became rougher and large holes appeared after synthesis. Zeta particle size analysis suggested that the particle size of AgNPs increased by 36.63 nm compared to HDL-03 EPS. FT-IR analysis exhibited that the position of the characteristic peaks of AgNPs changed. The OH moving from a wavelength of 3388.49 cm−1 to a wavelength of 3316.79 cm−1 and telescopic vibration peak changed from 1356.07 cm−1 to 1344.22 cm−1. A plate inhibition test revealed the effect of different concentrations of EPS and AgNO3 synthesized AgNPs on the diameter of inhibition circle produced by the indicator bacteria Escherichia coli and Staphylococcus aureus. Furthermore, AgNPs were applied to the indicator bacteria, which the minimum inhibitory concentration (MIC), time-inhibitory curve, and changes in extracellular conductivity, nucleic acids, proteins, ATP, and lactate dehydrogenase (LDH) levels were determined. The AgNPs inhibited the growth of E. coli and S. aureus and exhibited outstanding antimicrobial properties. With the increase of treatment time, the degree of cell membrane damage increased, the permeability enhanced, and the intracellular substances leaked. These results indicate that HDL-03 EPS has good potential for applications in the production of food packaging, antimicrobials, catheters, textiles and coatings.

Topological interpretation of black hole phase transition in Gauss–Bonnet gravity

Phase transitions of Einstein–Gauss–Bonnet black holes are studied using Duan’s [Formula: see text]-field topological current theory, where black holes are treated as topological defects in the thermodynamic parameter space. The kinetics of thermodynamic defects are studied using Duan’s bifurcation theory. In this picture, a first-order phase transition between small/large black hole phases is interpreted as the interchange of winding numbers between the defects as a result of some action at a distance. We observe a first-order phase transition between small/large black holes for [Formula: see text] Einstein–Gauss–Bonnet theory similar to Reissner–Nordström black holes in AdS space. This implies that these black hole solutions share the same topology and phase structure. We have also studied the phase transition of neutral black holes in [Formula: see text] and found a transition between unstable small and large stable black hole phases similar to the case of neutral black holes in AdS space. Recently, it has been conjectured that black holes with similar topological structure exhibit the same thermodynamic properties. Our results strengthen the conjecture by connecting the topological nature of black holes to phase transitions.

Cobalt/Nitrogen-Doped carbon hollow spheres for highly efficient degradation of tinidazole with peroxymonosulfate

This study aimed to put forward a strategy to synthesize cobalt/N-Doped carbon hollow spheres (Co/NCHPs) with ample reactive sites. The zeolitic imidazolate framework-67 was loaded on the polystyrene nanosphere (PS@ZIF-67) as precursors, followed by a controlled pyrolysis to obtain Co/NCHPs with a large single hole on each sphere. The 1O2, SO4•−, O2•−, and •OH were identified as the main reactive oxygen species (ROSs) by electron paramagnetic resonance (EPR) experiments. It is also worth noting that electron transfer was also the main non-radical pathway for tinidazole (TNZ) degradation in Co/NCHPs/PMS systems. The effects of reaction conditions on TNZ degradation were investigated. 20 mg/L of TNZ was degraded within 6 min under UV–visible light irradiation. Besides, the degradation efficiency of four organic pollutants was higher than 95 % in different water matrices. Moreover, Co/NCHPs exhibited an exceptional photocatalytic performance for several antibiotics and organic dyes mixed solution in natural water. Furthermore, the recycling test of Co/NCHPs indicated that catalysts can be reused five times without obvious activity loss. This work provided a facile and large-scale preparation method to obtain Co/NCHPs.

Improving flatness of machined surface in rotating cathode electrochemical milling

Electrochemical milling has broad application prospects for machining large aeronautical thin-walled components. This is because this technique has no cutting force, has no heat-affected zones, and is considerably flexible. In contrast to the non-rotating tool cathode of traditional electrochemical milling, the rotating cathode used in electrochemical milling has more promising prospects because it has the same motion mode as the milling cutter employed in mechanical milling. However, because of the uneven electric quantity supply from the cylindrical rotating cathode, the machined surface typically has a curved profile with inadequate surface flatness; this is the main drawback of rotating-cathode electrochemical milling. To improve the flatness of surfaces processed by rotating-cathode electrochemical milling, a novel multichannel cathode with the outlet hole arrangement that can improve the uniformity of electric quantity supply is proposed. Numerous large outlet holes are bored at the bottom center of multichannel rotating cathode. Numerical simulation results indicate that these holes cause a decrease in the electric quantity supply from the inner area at the bottom of the cathode from the perspectives of electric and flow fields, minimizing the unevenness of the electric quantity supply distribution. Validation experiments prove that compared with previously reported rotating cathodes, the straightness index and depth error of the surface machined by novel multichannel cathode are reduced by 80.9 % and 69.4 %, respectively. After obtaining grooves with flat surfaces, the step-over distance required to machine a plane using a multichannel rotating cathode increases; meanwhile, the flatness of the machined plane significantly improves. With the applied voltage of 25 V, electrolyte pressure of 0.2 MPa, initial inter-electrode gap of 0.2 mm, and cathode rotational speed of 500 rpm, a 42 × 40 mm plane is finally machined, whose planeness index (Δhp) is only 0.047.

Hole-edge crack monitoring in attachment lug with large bolt hole based on guided wave and circular piezoelectric sensor array

The crack damage monitoring of aircraft structures is very significant for ensuring aircraft safety, reducing maintenance costs and extending service life. Due to the extreme service environment, the attachment lug is prone to initiate crack damage at the hole edge, which leads to crack propagation and fracture failure. Structural health monitoring technology based on piezoelectric guided wave has been widely studied, promoting the development of crack monitoring. However, at present, research on hole-edge crack damage monitoring of attachment lugs still needs to be further carried out. It is difficult to monitor small cracks at the initial stage of crack propagation, and the accuracy of crack monitoring needs to be improved. By focusing on the accuracy of the crack monitoring in the attachment lug, a crack damage monitoring method based on the circular piezoelectric sensor array is proposed in this paper. Combined with damage alarming and localization imaging, this method comprehensively evaluates the hole-edge crack damage monitoring situation and improves the monitoring effect. The method is verified by an experiment in attachment lug, and this verification includes small crack monitoring and crack propagation monitoring. The experimental results demonstrate that this method can achieve correct damage alarming results, and the maximum localization error of crack damage is only 3.02 mm, which provides a research idea for the accurate monitoring of crack damage at the hole edge.

Investigation of black hole complementarity in AdS2 black holes

Black hole complementarity plays a pivotal role in resolving the information loss paradox by treating Hawking radiation as carriers of information, apart from the complicated mechanisms involved in decoding information from this radiation. The thought experiment proposed by Susskind and Thorlacius, as well as the criteria set forth by Hayden and Preskill, provide deep insights into the intricate relationship of black hole complementarity between fiducial and infalling observers. We execute the Alice-Bob thought experiment in the context of two-dimensional anti-de Sitter black holes. It turns out that information cloning can be avoided in the case of a large black hole. According to the Hayden-Preskill criteria, if the scale parameter associated with the explicit breaking of the one-dimensional group of reparametrizations is significantly exceed the squared mass of the black hole, then information cloning can be effectively evaded.

A comprehensive evaluation of the most-sold baby diapers on the market

The performance of baby diapers is highly related to the occurrence of diaper rash. However, a comprehensive evaluation of baby diapers on the market is unavailable. Herein, we systematically investigated the performance of the six most-sold baby diapers on the market. We disassembled the selected diapers and investigated the structure and properties of the main components, including the top sheet, acquisition sheet, absorbent core, and back sheet. Then the urine absorption capability, excrement spreading capability, run-off, and wetback of the diapers were investigated using urine and loose stool to reflect the functions of diapers in practical usage. Our results indicated that the performance of baby diapers is highly dependent on the structure and properties of each diaper component. Specifically, excrement run-off and wetback were highly related to excrement absorption speed and excrement spreading properties, respectively, which depend on the complex interactions among the top sheet, acquisition sheet, and absorbent core. In particular, designing the top sheet with a three-dimensional convex–concave structure or large holes was beneficial to fast excrement penetration. Meanwhile, employing an acquisition sheet could improve the excrement spreading properties. In addition, an absorbent core with a high content of super absorbent polymer and an absorption channel also contributed to a better excrement absorption property. Notably, Pampers and Moony diapers exhibited relatively low urine wetback. Bobdog and Babycare diapers showed 0 g urine run-off. Besides, Huggies, and Moony diapers were relatively soft, which could provide a better contact feeling during usage. Furthermore, Beaba diapers exhibited the best air permeability of 42.511 mm s−1 due to the existence of more breathable holes. Our study may provide scientific inspiration for researchers and enterprises to develop next-generation high-performance baby diapers and serve as a guideline for consumers to choose the right baby diapers.

Effect of Carbon on Sintering Behavior of Chromite‐Based Ladle Filler Sands

To investigate the effect of carbon on the sintering behavior of ladle filler sands, laboratory experiments are carried out using chromite‐based filler sands and carbon (graphite) powders as well as liquid steel in an inert atmosphere at 1600 °C. It is found that the fine carbon powders result in an increase in angle of repose before sintering. After sintering, the apparent porosity increases with the carbon content in the sands, while the bulk density declines. During sintering with and without liquid steel, the carbon powders in the sands will react with the sand grains, leading to the generation of some gases (CO and CO2) and the increase of liquid phase in the sands. The acceleration of the formation of the liquid phase in the sands would enhance the sintering of the sands. The generated gases can result in many large holes in the sands, and liquid steel is very possible to infiltrate into the sands. To obtain a higher ladle free opening rate, special attention should be paid to carbon addition in ladle filler sands.

Experiment analysis on defects in ultrasonic-assisted drilling of carbon fiber reinforced plastic with different diameter drills

Carbon fiber reinforced polymers (CFRP) are increasingly used in aerospace, military, and automotive applications due to their high specific strength and corrosion resistance. CFRP components usually require small-hole machining before assembly. CFRP parts are susceptible to defects such as tears and uncut fibers during hole machining. Ultrasonic-assisted drilling (UAD) contributes to the suppression of their defects. However, preliminary experiments revealed that the effect at different diameters is not the same. Therefore, this paper innovatively compares the effect of ultrasonic-assisted machining on the suppression of defects under different hole diameters and investigates the mechanism. The effects of machining parameters such as ultrasonic power, feed rate, and rotational speed on burr and tear defects of holes under different hole diameters are experimentally studied and theoretically analyzed. It was shown that the lowest defective machined holes were obtained at 50% (4 μm) ultrasonic power for all hole diameters, while higher ultrasonic power would result in an increase in machining defects. Compared with small hole diameters, there are relatively fewer uncut fibers at large hole diameters, but the tearing defects are more severe. The defect suppression effect of ultrasound is more pronounced at larger holes. The change in cutting force due to ultrasound is an important reason for the difference in machining defects. At a diameter of 6 mm, the longitudinal cutting force decreased by 58.7%, while uncut fibers and tearing defects decreased by 45.1% and 12.6%, respectively. This study can provide a theoretical basis for the selection of ultrasonic power and other parameters when machining holes of different diameters.

Effects of nanosized organic‐rectorite fillers on the morphologies and properties of PVDF UF membrane

AbstractIn this study, polyvinylidene fluoride/organic rectorite (PVDF/OREC) organic–inorganic nanocomposite membrane was prepared by phase conversion method. TEM and X‐ray diffraction (XRD) results demonstrate the successful fabrication of nanocomposite ultrafiltration membranes. When the OREC is less than 3 wt%, the nanosheets are mainly stripped and dispersed in the polymer matrix, with different numbers of intercalations. When the impurity content is 5%, the intercalation distribution dominates. When the impurity content increases to 7% and above, it becomes increasingly difficult for PVDF chain segments to enter the OREC interlayer and the OREC particles are dominated by simple blends on the order of micrometers in the polymer matrix. The inclusion of inorganic fillings significantly improved the mechanical properties of the membrane. The yield strength and tensile modulus of the membrane were increased by 53.7% and 574.9%, respectively, with an inorganic filler content of 5 wt%, while the elongation at the break was slightly decreased to 16.2%. This suggests a strong interaction between the OREC nanosheets and the polymer matrix. XRD and FTIR analyses indicate that OREC particles are effective heterogeneous nucleating agents that favor the formation of β‐phase crystals in the film. SEM surface and cross‐section results show that when joining can significantly reduce the average pore size of the membrane surface, large holes tend to reduce the number of holes in the skin layer distribution more uniformly. The AFM results show that the addition of OREC can significantly alter the surface roughness of ultrafiltered membranes, and that the changes in surface roughness and surface pore morphology of membranes with different clay contents are closely related to the distribution of nanoscale silicate sheets in the PVDF matrix.Highlights Prepared PVDF/OREC nanocomposite membranes via a phase‐inversion process. OREC acted as a potent nucleation agent, favoring β crystal formation. OREC resulted in smaller pore sizes and fewer large pores in the skin layer. The hydrophilicity of PVDF membranes was reformative by filling OREC. OREC led to increased water flux and BSA rejection due to pores and hydrophilicity.