Side Walls Research Articles

Development of an Autonomous Mobile Robot to Transport Heavy Objects on Narrow Alleys and Steep Slopes

ABSTRACTIn this study, we developed a four‐wheel‐driven autonomous mobile robot to transport heavy objects on narrow alleys and steep slopes. The robot, which weighs 450 kg, is driven by four 650 W hub motors to climb 20° steep slopes and travel through a narrow alley. Two 2D‐LiDARs attached to the front and rear of the robot body are used for highly accurate driving. A method based on the least squares approach for estimating the position and posture of the robot body is proposed by using the point cloud information of the side wall of the narrow alley. Field experiments on test courses demonstrated that the autonomous robot could transport heavy objects over steep slopes and travel in a narrow alley with high accuracy.

Abstract 4122350: Most Diabetes Mellitus Patients Had Right Lower Pulmonary Vein Thrombi; Additionally, Many Patients Had Extended Large Rod-Like Thrombi in the Left Atrium

Background: Retrieved thrombus studies have shown that retrieved thrombi have calcifications, indicating that the thrombi are old. Left atrium diverticula (LADs) are common; however, the mechanisms of LAD formation are poorly understood. Pulmonary vein thrombi (PVTs) are common and are underestimated. In 2022, we reported that 98.6% of senior patients with age-related diseases such as hypertension, dyslipidemia and atrial fibrillation had PVTs, as estimated by cardiac computed tomography (CT) and transesophageal echocardiography (TEE). Additionally, we reported a case in which a malignant lymphoma patient had ATs in the right lower pulmonary vein, in which extended large rod-like thrombi in the left atrium (LA) were found, as determined by TEE. Patients with type 2 diabetes mellitus (T2DM) must have PVTs. The characteristics of extended LA thrombi in patients with T2DM are unclear. Methods: Thirty-one patients with T2DM (73.5 +/- 8.9 y.o., from 50 y.o. to 88 y.o.; male, 24) were examined for PVTs, as estimated via TEE and cardiac CT. Results: Thirty (97%) patients with T2DM had PVTs in the right lower pulmonary vein (RLPV) and connected LA thrombi, as estimated using TEE. Among them, 27 (87%) patients had large white rod-like LA thrombi extending from RLPV thrombi, and the diameter of the thin part of the rod-like LA thrombi was approximately 5 mm. The end of the LA thrombi was mainly attached to the left side of the anterior wall or the posterior side of left side wall of the LA. Additionally, there were left atrium diverticula (LADs) around the attachment regions. Three patients had RLPV thrombi and connected shorter LA thrombi. A 79-year-old male patient did not have detectable PVTs. The patient had taken apixaban (2.5 mg, twice daily) for six years due to atrial fibrillation and stroke. Conclusions: Most (97%) elderly T2DM patients had RLPV thrombi. Additionally, many (87%) patients had extended large rod-like thrombi in the LA. The diameter of the thin part of the large rod-like LA thrombi was approximately 5 mm. There were LADs around the attachment regions where the ends of the LA thrombi from the RLPV thrombi were attached.

Kinematics of the First Wave Faraday Mode on the Side Wall of a Rectangular Vessel

Kinematics of the First Wave Faraday Mode on the Side Wall of a Rectangular Vessel

The Sternocleidomastoid Muscle Reverse Pad: A “Safety Net” in Catastrophic Tracheal Surgery Situation

Background: This paper presents the outcomes of employing the inferiorly based rotated sternocleidomastoid muscle flap in complex tracheal reconstruction/repair scenarios, focusing on the key objectives of ensuring stable airway, functional digestive tract and patient survival. Methods: A retrospective analysis was performed for patients treated at two medical centers (A.O. San Camillo Forlanini, Rome, and A.O.U. Careggi, Florence) from 2011 to 2023, in which the sternocleidomastoid muscle (SCM) flap, detached from the mastoid and basicranium, was rotated on the lower pivot directly onto the repair site and pedicled to the sternal origin to ensure the continuity of the airway. Average postoperative hospital stay, follow-up period and patient survival were analyzed. Follow-up assessments encompassed bronchoscopies and CT scans conducted at intervals of 15 and 28 days, and subsequently at 3 and 9 months. Results: A total of five patients were enrolled in this study. These cases included one patient with anterior tracheal wall lesions with abundant tissue loss, one patient with an anterior wall necrosis due to descending cervical mediastinitis and three patients with extra-long tracheoesophageal fistulas (TEFs) (greater than 4.5 cm or >30% of the total tracheal length). In the case of the direct repair of a TEF with a proximal tracheal stenosis, the sternocleidomastoid muscle was used to reconstruct the tissue deficit caused by extensive loss of substance in the left lateral side of the tracheal wall. In case of repair through exclusion of the TEF, the sternocleidomastoid muscle was interposed between the visceral sutures after exclusion of the TEF by an endomechanical device, in one case even substituting the membranous part of the tracheal wall. Our technique allows rotation on the sternal head of the sternocleidomastoid muscle with the lowest rotation radius, pedicled to the sternal origin, detached from the mastoid process and superior nuchal line, thus providing optimal vascularization from the superior thyroid artery/external carotid artery and accessory vasculature from the suprascapular artery. Patients exhibited uneventful postoperative recovery concerning airway and digestive patency. The mean postoperative hospitalization duration was 41 days. The follow-up assessments were negative for postoperative complications. Conclusions: The use of sternocleidomastoid muscle flap was proposed to ensure repair and protection of the suture margin or to constitute a portion, as a scaffold, of the wall by leveraging the muscle’s vascularization and thickness. This technique may be considered a leading component in managing complex situations in tracheal surgery.

Dynamics of a hot flexible cantilever plate under natural convection heat transfer in a square cavity

This study investigates the fluid-structure interactions of a flapping plate within a square cavity under four distinct boundary conditions, where two opposing walls are heated isothermally, and the others are adiabatic. These configurations are defined as case 1 (cooled side walls), case 2 (cooled top and bottom walls), case 3 (heated bottom and cooled top wall), and case 4 (heated top wall and cooled bottom wall). The effects of non-dimensional parameters, including Rayleigh number (Ra), Cauchy number (Ca), and mass ratio (β) on plate dynamics and convective heat transfer are analyzed. Numerical investigations are executed utilizing the SU2 open-source multi-physics computational fluid dynamics solver, with a fixed Prandtl number (Pr) set at 0.71 and dimensionless temperature difference (ϵ) established at 0.6. The results show that in cases 1 and 4, the plate exhibits no observable unsteadiness, while cases 2 and 3 reveal different oscillatory behavior within certain parameter ranges, including static mode, periodic flapping mode, quasi-periodic flapping mode, and chaotic flapping mode. In particular, the configuration in case 3 possesses higher inherent instability than case 2, causing the earlier onset of Hopf bifurcation. These findings provide valuable insights into the influence of boundary conditions on the behavior of flexible structures in fluid environments, highlighting the critical role of flow instabilities and boundary conditions in determining the dynamic response of the system.

On the use of hydrogen in oxy-fuel glass melting furnaces: An extensive numerical study of the fuel switching effects based on coupled CFD simulations

The present study examined the potential of utilizing hydrogen as a fuel in an industrial cross-fired oxy-fuel glass melting furnace with a total energy input of 3.9 MW. To this end, comprehensive three-dimensional CFD simulations were performed in Ansys Fluent, employing a coupled numerical model from preceding works. A two-step validation process was presented, comprising the validation of both the numerical furnace setup and the modeling of industrial oxy-fuel combustion setups using hydrogen as a fuel gas. Assuming an equal thermal energy input for both combustion conditions, the fuel/oxidizer ratios of velocity and momentum of the six PrimeFire burners were found to be significantly affected. Consequently, the low-momentum flames with natural gas transformed into jet-type flames with a straighter trajectory when transitioning to hydrogen. This change led to an enhanced turbulent mixing and a reduction of flame lengths by over 25%, while the average flame temperature increased by up to 82 K due to the accelerated reaction kinetics. In addition, the elevated flame momentum in the cross-fired burner configuration resulted in a localized rise in maximum side wall temperatures by more than 20 K. With the exception of these local effects, the global temperature distribution and heat transfer mechanisms were not significantly impacted. This indicated a comparable melting process and furnace efficiency, while still allowing for a reduction of total CO2 emissions by 77.5%. Future research should concentrate on both the impact on glass quality and the evaluation of potential alternative burner configurations for hydrogen-fired oxy-fuel glass melting furnaces.

Improving non-uniform gravelly sand using microbially induced carbonate precipitation: An outdoor cubic-meter scale trial by engineering contractors

Soil improvement using microbially induced carbonate precipitation (MICP) remains largely confined to the laboratory, with only a very small number of large-scale experiments having been completed under field conditions and none by engineering contractors. This study presents a cubic-meter scale improvement of heterogeneous natural sand collected from a local quarry, with a wide variation in grain size, via MICP. The MICP trial was conducted by engineering contractors in a cubic test cell under variable temperatures ranging from 5 °C to 19 °C. The upscaling of cultivation of Sporosarcina pasteurii (600 L for each treatment cycle) under non-sterile conditions, as performed by engineering contractors, achieved an optical density (OD600) of 0.89 and a specific urease activity of 2.5 mM urea/min/OD600. Post-MICP-treated sands were subjected to a series of coring, block sampling and laboratory tests. The block sampling process indicated that the majority of sand was effectively cemented, with a small region near a side wall forming a less well-cemented zone, likely induced by less effective fluid delivery in this region. The unconfined compressive strengths of three cores (diameter: 10 cm, length: 22 cm) were 3.6, 4.4, and 7.6 MPa. Consolidated-drained triaxial tests on sub-sampled cores also demonstrated rock-like material behaviour, with a peak friction angle of 43.6° and peak cohesion of 0.64 MPa, and ultimate state frictional angles of 42.0° and ultimate cohesion of 0.12 MPa. The increased shear parameters of the bio-cemented samples (relative to the untreated samples) have many implications for mitigation of geotechnical hazards such as soil liquefaction. The study marks a step forward industrial implementation of MICP for soil improvement by engineering contractors without prior knowledge of MICP.

Mass discharge rate of granular flow in eccentric silos with variable side wall friction

There are many studies on the effect of side wall friction on mass discharge rate (MDR), but the physical mechanism is lacking. In this paper, by changing side wall friction of eccentric silos, the relationship between macroscopic MDR and microscopic frictional coefficient was established, and the regulation of MDR up to a range of 40 % was realized. Furthermore, it is revealed that the variation of MDR is caused by the change in geometric structure of free-fall arch (FFA). In addition, the velocity of particles on FFA is the same under different MDR. The reason is that under high frictional coefficient, the gravitational potential energy of particles is more dissipated in the rotational motion caused by resistance. This work explains for the first time the mechanism of the frictional coefficient on MDR, and provides a data reference for improving the theoretical model of MDR.

Shape-dependent aerosol dynamics in indoor environments: Penetration, deposition, and dispersion

Particle shape exerts a significant influence on their dynamic behavior, and it is imperative to elucidate these effects given the potential for severe environmental toxicity associated with shaped particles. Despite extensive research on the dynamical processes of spherical particles, the behaviors of non-spherical particles have been insufficiently investigated. In this study, we have developed a suite of computation-based models that account for particle shape and have reported on the typical dynamical behaviors of non-spherical particles within indoor environments. We have explored three typical scenarios, i.e., particle penetration into indoor spaces through building cracks, indoor particle deposition, and indoor particle dispersion. The shape-induced deviations are associated with dynamical processes, showing a decrease trend among penetration, deposition, and dispersion of the non-spherical particles. The maximum discrepancy due to particle shape during the penetration process exceeds 1000 %, observed with particles of approximately 0.02 μm in diameter interacting with straight cracks 4.5 cm in length and 0.25 mm in height. Moreover, there is a discrepancy of more than 70 % in the deposition of particles with a diameter of approximately 10 μm on side walls when using side air supply ventilation. Similarly, a discrepancy of nearly 11 % is noted for particles around 0.02 μm in diameter during dispersion under displacement ventilation within indoor settings. The interaction between shape-related particle dynamics, particularly their diffusion characteristics, and the properties of the flow field leads to these shape-dependent dynamical discrepancies. These findings offer a comprehensive understanding of how the shape of particles affects their indoor dynamic behavior, thereby supporting the control of hazardous particles in indoor environments.

Left atrial appendage anatomy: clinical implications for cardiac procedures.

The Left Atrial Appendage (LAA) is the most common source of thrombi during atrial fibrillation (AF) leading to stroke. With the increasing prevalence of AF and the growing number of patients requiring LAA involved interventions like exclusion and ablation, understanding LAA's anatomical intricacies becomes paramount importance. This study aims to provide anatomical data regarding LAA in relation to these procedures. Total 50 formalin-fixed cadaveric hearts were examined and various morphological and morphometric parameters were noted. The Cauliflower shape LAA (36%) was most common followed by Chicken Wing (34%), Cactus (18%), and Windsock (12%) shapes. The LAA orifice had greater horizontal diameter compared to the vertical diameter and was oval in shape in 64% cases. Diverticular structures called divots/ pits were present surrounding the LAA orifice in 36% cases with high variation in number, size, and distance from orifice. They were most commonly present towards the septal side and posterior wall side around the LAA orifice. The circumflex artery was the closest structure to LAA orifice with less than 5mm distance in 76% cases. Other structures present close to the LAA were the Left Superior Pulmonary Vein and Mitral Valve. According to shape, the Non-Chicken Wing morphology of the LAA was associated with close running left circumflex artery, high OI (Ovality Index) of the orifice, and greater presence of divots. The LAA anatomy is complex with high amount of variability making it difficult to perform successful procedures. Given data can help clinicians in better planning and execution of cardiac interventions involving the LAA.

Research on the Construction Mechanics and Stability Control Technology of Expressway Tunnel Based on Numerical Analysis

As an effective structural form, connecting arch tunnel has been widely used in practical engineering because of its smooth linear shape, small footprint and good bridge and tunnel connection. With the increase of domestic traffic volume year by year, the width of the even arch tunnel is gradually changed from two-way four lanes to two-way six lanes. I20 I-steel, spacing 0.75∼1 m, anchor length 3∼4 m, ring spacing 0.5∼1 m, the side ring spacing of the middle wall is 0.75 m, the side ring spacing of the side wall is 1 m, and the shotcrete thickness is 0.25∼0.3 m. The excavation span of a two-way six-lane continuous-arch tunnel is considerable, leading to complex stress characteristics, thereby posing risks to construction safety and structural stability. Following the construction of the initial tunnel, disturbance to the surrounding rock occurs, affecting subsequent excavation phases. The initial support requirements for subsequent excavations are more intricate, with increased internal forces compared to the initial tunnel segment. As the rear tunnel progresses, the surrounding rock near the middle wall shifts towards the rear tunnel, reducing internal forces in the concrete and steel arch frame. However, as the rear tunnel distance increases, concrete stress and axial forces on the middle wall side of the initial tunnel begin to rise. Throughout the construction, the steel arch frame’s internal forces and spray concrete stress on the middle wall side’s arch waist and foot are the highest, making them susceptible to disruption from construction on the opposite side, thus constituting critical tunnel components. Numerical simulations effectively capture surrounding rock and structural stress dynamics during large-span arch tunnel construction. Simulation outcomes align closely with field measurements, particularly in three-dimensional simulations, enhancing construction understanding and management.

Preliminary application results of laparoscopic assisted proximal gastrectomy λ-shaped double tract anastomosis

Objective: To share the results of laparoscopic assisted proximal gastrectomy λ- shaped modified double tract reconstruction. Method: This study retrospectively included 3 patients during January 2024 from the Department of Gastric Surgery at the First Affiliated Hospital of Nanjing Medical University using the λ-shaped modified double tract reconstruction. The procedure of the λ-shaped modified double tract reconstruction is as follows. After completing proximal gastrectomy, the jejunum is transected 15 cm from the Treitz ligament. A suture is made 18-20 cm from the distal jejunum to mark the esophagojejunal anastomosis site. A circular stapler anvil is inserted through the distal jejunum, and the remaining end of the jejunum is turned to the right. The circular stapler is pierced through the marked site for an esophagojejunal end-to-end anastomosis, which is reinforced with a barbed suture continuously. A 60mm linear stapler is used to close the remaining end of the jejunum. We then mark the gastric side of the gastrojejunal anastomosis with suture in the middle of the anterior wall of the residual stomach, and mark the jejunal side of the gastrojejunal anastomosis at a distance of about 2 cm and 8 cm from the residual end of the distal jejunum. We make an opening of about 0.5 cm and use a 60 mm linear stapler to perform anastomosis on the jejunal side of the anterior wall of the residual stomach according to the markings, so that the distance between the esophagojejunal anastomosis and the gastrojejunal anastomosis is 10-12 cm. The common opening is closed with barbed wire. About 50 cm below the esophagojejunal anastomosis, the small intestine opening is anastomosed side to side using a circular stapler and the common opening is closed. Return the jejunum into the abdominal cavity to complete the reconstruction of the λ-shaped double tract reconstruction. We analyzed the surgery and postoperative conditions, including surgery time, anastomosis time, intraoperative bleeding, tumor size and pathology, postoperative mobilization, passage of gas and water intake time, discharge time, postoperative complications, and postoperative gastrointestinal imaging to observe the passage of food through the gastric and intestinal loops. Results: Three patients successfully received laparoscopic assisted proximal gastrectomy with λ-shaped modified double tract reconstruction. The surgical time was 155 minutes, 240 minutes, and 160 minutes, respectively; The postoperative time for first ambulation was 20 hours, 18 hours, and 26 hours, respectively. The time for passage of gas was 59 hours, 83 hours, and 75 hours, respectively. The drinking time was 66 hours, 87 hours, and 90 hours, respectively. The postoperative discharge days were all 7 days. No surgical related complications occurred. On the 6th day and 3 months after surgery, gastrointestinal angiography was performed. The contrast agent passed smoothly through the jejunal loop and residual stomach jejunal loop, and both sides were unobstructed. No contrast agent was found to retrograde to the esophagojejunal anastomosis. Conclusion: Laparoscopic assisted proximal gastrectomy with λ-shaped modified double tract reconstruction is safe and feasible, as it improves the diversion of food through the residual stomach while ensuring anti-reflux effects.

Short-term effects of laparoscopic sleeve gastrectomy combined with reconstruction of the acute His angle on postoperative gastroesophageal reflux disease

Objective: To compare the short-term efficacy of laparoscopic sleeve gastrectomy (LSG) combined with sharp His angle reconstruction (LSG-His) versus traditional LSG. Methods: In this retrospective cohort study we collected clinical data of patients with obesity who had undergone LSG or LSG-His in the Department of General Surgery, Beijing Chaoyang Hospital, Capital Medical University, from January to June 2022. After excluding patients with incomplete follow-up data and those with hiatal hernia, 83 obese patients, of which 39 who had undergone LSG (LSG group) and 44 who had undergone LSG-His (LSG-His group), were included in the study. The basic steps in LSG-His are the same as in conventional LSG. After continuous suturing of the gastric staple line, one stitch is placed between the proximal side of the gastric greater curvature staple line and the proximal side of the gastric fundus posterior wall with the left diaphragm, and another stitch between the right side of the gastric fundus and the esophagus, reconstructing the sharp His angle. Clinical data, postoperative complications, and follow-up data on weight loss and gastroesophageal reflux disease (GERD) symptoms 1-, 3-, 6-, and 12-months post-discharge were compared between the two groups. GERD symptoms were assessed using the Gastroesophageal Reflux Disease Questionnaire and Reflux Diagnostic Questionnaire. Results: There were no significant differences between the two groups in baseline characteristics, length of hospital stay, hospitalization costs, intraoperative bleeding, postoperative nausea and vomiting, dysphagia, or postoperative complications (all P>0.05). Compared with the LSG group, the LSG-His group had significantly longer operative times (92 [80, 100] minutes vs. 80 [70, 100] minutes, U=2.227, P=0.026), higher postoperative 24-hour pain scores (5.2±1.8 vs. 4.3±1.9, t=-2.065, P=0.041), and higher rates of morphine use (70.5% [31/44] vs. 46.2% [18/39], χ²=4.519, P=0.025). The incidence of new-onset GERD 12 months postoperatively was significantly lower in the LSG-His than the LSG group (10.7% [3/28] vs. 61.3% [19/31], χ²=14.00, P<0.001). According to changes in Gastroesophageal Reflux Disease Questionnaire and Reflux Diagnostic Questionnaire scores, the LSG-His group also had significantly lower rates of exacerbation of GERD (2/16 vs. 5/8, χ²=4.27, P=0.021) and higher rates of GERD remission (12/16 vs. 2/8, χ²=3.62, P=0.032) than did the LSG group. Additionally, excess weight loss rates were significantly higher in the LSG-His group at 3 months [(54.7± 18.7)% vs. (46.5±15.0)% , t=-2.166, P=0.033], 6 months [(73.8±24.7)% vs. (64.0±19.1)% , t=-2.018, P=0.047], and 12 months [(82.9±26.7)% vs. (72.2±19.3)%, t=-2.063, P=0.042] than in the LSG group. Conclusion: Compared with LSG, LSG-His is safe and feasible and achieves better short-term control of postoperative GERD and more effective weight loss. Further large-scale, long-term, prospective studies are needed to confirm the long-term efficacy of LSG-His.

Ремонт деталей авіаційних двигунів із жароміцних нікелевих сплавів із застосуванням адитивних плазмових технологій

In order to improve the maintainability of aircraft engine parts, the article examined the use of additive technologies in repairs. The article establishes that the use of additive technologies by the method of plasma surfacing in the repair of aircraft engine parts, such as turbine blades, sealing discs, NA parts, is very promising and will significantly increase the percentage of parts and assemblies restored after operation, which have a significant area of damage. Turbine blades are made of nickel heat-resistant alloys with a polycrystalline structure (ЖС6К-ВИ, ЖС6У-ВИ), or from alloys with directional crystallization (ЖС32-ВИ, ЖС26-ВИ). After operating for more than 6 thousand hours, in addition to the operational wear of the ends and side walls of the shroud flanges, thermal fatigue cracks up to 6 mm deep are observed on the blades received for repair. The technology of argon-arc surfacing and the surfacing materials existing for this process do not provide the heat-resistant properties of the restored surface necessary for the operation of the blades. The solution to the problem was achieved through the use of a compressed arc source with precision adjustment of the welding current and mechanization of the supply of filler material (powder), which would make it possible to surfacing with a limited penetration depth and, accordingly, mixing the deposited material with the base metal. The developed technology made it possible to restore damaged sections of blades after operation (shroud flanges, labyrinth scallops, z-shaped profiles and airfoil ends) on heat-resistant alloys using filler material equal to the strength of the base metal. For this process, powders of nickel and cobalt alloys with a fraction of +63...-160 microns are used, obtained by atomization with a jet of inert gas (argon). The main powders used are ЖС32-ВИ, ЖС6К-ВИ, В3К, Stellite 12, Stellite 6, ХТН61. Disc material – ЭП742-ИД. Working medium, air, oil and combustion products. The maximum heating temperature of labyrinth scallops is up to 680 ºC at a maximum medium pressure of up to 1.47 MPa. The maximum peripheral speed of the scallop end is 251 m/s. Material of seal mating parts ЭИ435 (cell δ = 0,1 mm). When developing the technology, the successful experience of restoring labyrinthine scallops of turbine blades was taken into account. The restoration of the labyrinthine ridges of the disk was carried out using a compressed arc source with precision control of the welding current and a robotic installation, which included a robot for moving the plasma torch and a manipulator for rotating the disk. This made it possible to carry out surfacing with a limited penetration depth and obtain a uniformly directed bead over the entire diameter of the disk. Testing of the restored disk in order to verify its performance was carried out as part of a run-in aircraft engine. To do this, after the next assembly of the run-in engine, the disk was installed in the MPT rotor. The test was carried out in 5 cycles, the duration of each cycle was 15 hours. No wear of the labyrinth ridges or cracks was detected. The functionality of the restored disk has been confirmed. NA parts are made of heat-resistant, low-aging, high-chromium nickel-based alloy ЭП648-ВИ. They operate in hot engine conditions at temperatures up to 900'C. As a result of operation, both end surfaces and flat surfaces in the tract area are subject to wear. To restore parts of the NA, the technology of additive growth by the method of microplasma powder surfacing was used. To confirm the operability of restored parts, a set of studies of samples grown using the same repair technology was conducted. At the same time, it was established that the chemical composition of the deposited metal corresponds to the requirements of the technical conditions-» the microstructure of the deposited metal after heat treatment corresponds to the normal heat-treated state of the alloy ЭП648-ВИ (ХН50ВМТЮБ-ВИ), the level of mechanical properties of the grown alloy with subsequent serial heat treatment (aging at 700ºC, exposure -16 hours) is not lower than the forging level used in serial production of the part.

The behaviour of micro-injection moulding inserts produced with material jetting technology

The increasing interest in additive manufacturing and advancements in precision and production quality have sparked attention to its use in industrial prototyping. High-performance polymer resins enhance flexibility in mass production processes like micro-injection moulding. This flexibility allows for reconfigurable moulds using resin inserts, enabling the transition of devices, such as microfluidics, from labs to large-scale production. Despite progress, limitations exist in additive manufacturing, including the minimum size of microstructures and the brittle behaviour of resin inserts during moulding cycles, impacting overall production capacity. This study focuses on using a micro-injection moulding machine to reproduce PMMA thin plates with single straight microchannels (250 μm) and with different side wall angles (0°, 15°, and 30°), investigating the best compromise between capability and insert resistance to moulding cycles. A careful study of the dynamics leading to the insert failure and the resin limits was carried out. The results showed that it is possible to produce about 15 micro-structured thin plates with good accuracy using a resin insert realised with Material Jetting technology.

Follicle-intrinsic and spatially distinct molecular programs drive follicle rupture and luteinization during ex vivo mammalian ovulation

During ovulation, the apical wall of the preovulatory follicle breaks down to facilitate gamete release. In parallel, the residual follicle wall differentiates into a progesterone-producing corpus luteum. Disruption of ovulation, whether through contraceptive intervention or infertility, has implications for women’s health. In this study, we harness the power of an ex vivo ovulation model and machine-learning guided microdissection to identify differences between the ruptured and unruptured sides of the follicle wall. We demonstrate that the unruptured side exhibits clear markers of luteinization after ovulation while the ruptured side exhibits cell death signals. RNA-sequencing of individual follicle sides reveals 2099 differentially expressed genes (DEGs) between follicle sides without ovulation induction, and 1673 DEGs 12 h after induction of ovulation. Our model validates molecular patterns consistent with known ovulation biology even though this process occurs in the absence of the ovarian stroma, vasculature, and immune cells. We further identify previously unappreciated pathways including amino acid transport and Jag-Notch signaling on the ruptured side and glycolysis, metal ion processing, and IL-11 signaling on the unruptured side of the follicle. This study yields key insights into follicle-inherent, spatially-defined pathways that underlie follicle rupture, which may further understanding of ovulation physiology and advance women’s health.

Impact of 6-OHDA injection and microtrauma in the rat substantia nigra on local brain amyloid beta protein concentrations in the affected area.

Amyloid beta peptides (Aβ) are key indicators of Alzheimer's disease and are also linked to cognitive decline in Parkinson's disease (PD) and other neurodegenerative disorders. This study explored the accumulation of Aβ in a standard 6-Hydroxydopamine (6-OHDA) model of PD. We unilaterally injected 6-OHDA into the substantia nigra of Wistar rats to induce dopaminergic cell degeneration and death, a characteristic of PD. The goal was to detect Aβ protein in tissues and blood vessels showing inflammation or degeneration from the 6-OHDA injection. Our results showed that 6-OHDA injection produced a statistically significant rise in Aβ concentration at the injection site 60 minutes after injection, which was slightly reduced 24 hours post-injection but still significantly higher than in controls. We also tried Gp120 injection in the same zone but it only produced effects comparable to control needle trauma. The presence of Aβ in tissues and blood vessel walls after injection was confirmed through ELISA tests and was supported by immunohistochemical staining of injection areas. We found that the increased Aβ concentration was visible in and around blood vessels and inside blood vessel walls, and also, to a lesser extent in some cells, most probably neurons, in the area. This research highlights the connection between dopaminergic cell poisoning and the accumulation of Aβ, offering insights into the progression of PD to cognitive disorders and dementia.

Enhanced Acoustic Mixing in Silicon-Based Chips with Sharp-Edged Micro-Structures

The small dimensions of microfluidic channels allow for fast diffusive or passive mixing, which is beneficial for time-sensitive applications such as chemical reactions, biological assays, and the transport of to-be-detected species to sensors. In microfluidics, the need for fast mixing within milliseconds arises primarily because these devices are often used in fields where rapid and efficient mixing significantly impacts the performance and outcome of the processes. Active mixing with acoustics in microfluidic devices involves using acoustic waves to enhance the mixing of fluids within microchannels. Using sharp corners and wall patterns in acoustofluidic devices significantly enhances the mixing by acoustic streaming around these features. The streaming patterns around the sharp edges are particularly effective for the mixing because they can produce strong lateral flows that rapidly homogenize liquids. This work presents extensive characterizations of the effect of sharp-edged structures on acoustic mixing in bulk acoustic wave (BAW) mode in a silicon microdevice. The effect of side wall patterns in different angles and shapes, their positions, the type of piezoelectric transducer, and its amplitude and frequency have been studied. Following the patterning of the channel walls, a mixing time of 25 times faster was reached, compared to channels with smooth side walls exhibiting conventional BAW behavior. The average locally determined acoustic streaming velocity inside the channel becomes 14 times faster if sharp corners of 10° are added to the wall.

Blast wave ingress into a room through an opening – Review of past research and US DoD UFC 3-340-02

Blast wave ingress into a room through a facade opening results in complex pressure-time loadings on interior surfaces due to shock diffraction and interior reflections. The U.S. DoD UFC 3-340-02 Structures to Resist the Effects of Accidental Explosions includes a method to predict internal loading for such cases. Parameters such as the opening size, room dimensions and the external pressure wave characteristics influence the interior loading. Recent work suggests that the UFC methodology might overpredict the interior loading by some 600%. Such conservatism can result in over-engineered or prohibitively expensive protective solutions. In this paper we critically review the methodology of the UFC, that of Kaplan’s preceding work (on which the UFC relies), and the experimental data that informed both these works. Through a series of 45 case-studies we compare the UFC and Kaplan’s predictions with those of a computational fluid dynamics (CFD) model. The UFC consistently overpredicts the CFD area-averaged peak pressure of the back wall by up to 290% and the side-wall by up to 425%. Similarly, the UFC overpredicted the CFD side wall positive phase impulse by up to 565%. By contrast, the UFC predicted back wall positive phase impulse was similar to the CFD results. As our CFD results for side and back walls are area averaged, and not solely for the wall centre-point, as in other recent work, our paper gives support for the use of CFD prediction over the UFC for cost-effective design of structures to resist blast ingress.

Study on the wetting characteristics of liquid-Al/ SiO2 interface with Si content in liquid-Al

Aiming to address the issue of aluminum slag adhering to the interior walls of vacuum lifting ladles in the aluminum electrolysis industry, Molecular dynamics simulations are employed to investigate the wetting behavior and adhesion characteristics of aluminum droplets on silica surfaces. Our findings indicate that with an increase in silicon content within the droplets, wetting diminishes and complete wetting of the silica substrate by aluminum droplets is not achieved. The presence of silicon reduces both the melting point temperature and surface tension of aluminum droplets, leading to a significant increase in contact angle and a corresponding decrease in wettability. Moreover, an elevated silicon content within molten aluminum droplets substantially decreases their interaction energy with the substrate surface. The virtual wall method is applied to examine average separation force and work of separation for detaching aluminum droplets from the substrate, revealing that adhesion characteristics are predominantly governed by mutual adhesive forces. This paper presents an atomic-level analysis elucidating how silicon as an alloying element influences adhesion between liquid aluminum and solid surfaces.