Mechanical Factors Research Articles

Underwater Side-Scan Sonar Target Detection: YOLOv7 Model Combined with Attention Mechanism and Scaling Factor

Side-scan sonar plays a crucial role in underwater exploration, and the autonomous detection of side-scan sonar images is vital for detecting unknown underwater environments. However, due to the complexity of the underwater environment, the presence of a few highlighted areas on the targets, blurred feature details, and difficulty in collecting data from side-scan sonar, achieving high-precision autonomous target recognition in side-scan sonar images is challenging. This article addresses this problem by improving the You Only Look Once v7 (YOLOv7) model to achieve high-precision object detection in side-scan sonar images. Firstly, given that side-scan sonar images contain large areas of irrelevant information, this paper introduces the Swin-Transformer for dynamic attention and global modeling, which enhances the model’s focus on the target regions. Secondly, the Convolutional Block Attention Module (CBAM) is utilized to further improve feature representation and enhance the neural network model’s accuracy. Lastly, to address the uncertainty of geometric features in side-scan sonar target features, this paper innovatively incorporates a feature scaling factor into the YOLOv7 model. The experiment initially verified the necessity of attention mechanisms in the public dataset. Subsequently, experiments on our side-scan sonar (SSS) image dataset show that the improved YOLOv7 model has 87.9% and 49.23% in its average accuracy (mAP0.5) and (mAP0.5:0.95), respectively. These results are 9.28% and 8.41% higher than the YOLOv7 model. The improved YOLOv7 algorithm proposed in this paper has great potential for object detection and the recognition of side-scan sonar images.

Ferroelectric Polarization Dependent Piezoelectric Hardening in BiFeO3‐BaTiO3 Lead‐Free Ceramics

AbstractThe relation between the improvement of mechanical quality factor (Qm) and internal electric field (Ei) generated during the aging process in lead‐free piezoelectric BiFeO3‐BaTiO3 ceramics is investigated for hard piezoelectric application of power transducers. The change of built‐in Ei depends on the ferroelectric polarization (P) direction during the aging process. For the aging process with P parallel to Ei, Qm and Ei increases but Qm and Ei decreases with P antiparallel to Ei. These results are attributed to the migration of defects by depolarization fields and domain‐wall pinning. This work provides the systematic guidance to develop high‐power piezoelectric transducers with lead‐free ceramics.

Zinc isotope fractionation during coprecipitation with amorphous iron (hydr)oxides

Coprecipitation facilitates the incorporation of Zn into the lattice of Fe (hydr)oxide, which is a crucial mechanism causing low Zn bioavailability in widespread Zn-deficient soils. Zn isotopes are a potential indicator of the coprecipitation of Zn and Fe (hydr)oxides in soils. However, the Zn isotope fractionation caused by coprecipitation with amorphous Fe (hydr)oxides (e.g., ferrihydrite) and the impact of environmentally relevant conditions remain unknown. Here, the molecular mechanism and impact factor of Zn isotope fractionation during Zn2+-Fe3+ coprecipitation under natural soil conditions (including different pH values and initial Zn/Fe ratios) were investigated by combining isotope ratio measurements, extended X-ray absorption fine structure (EXAFS) analyses, and density functional theory (DFT) geometry optimization. The results show that aqueous Zn (Znaq) can be complexed on the ferrihydrite surface (Znads) with positive isotope fractionation (Δ66Znads–aq = 0.42 ± 0.09 ‰) or directly incorporated into the ferrihydrite lattice with slightly negative isotope fractionation (Δ66Znstru-aq = −0.08 ± 0.03 ‰). In addition, over time, the surface-complexed Zn can further transform to a layered structure on the surface but exhibits limited Zn isotope fractionation. According to Zn K-edge EXAFS, the Zn isotope fractionation of surface complexation and incorporation of Znaq are related to the decrease in the Zn–O bond strength in the order surface complexed Zn (RZn–O = 2.00 Å) > aqueous Zn (RZn–O = 2.08 Å) > directly incorporated Zn (RZn–O = 2.06–2.07 Å with slight distortion). The limited Zn isotope fractionation associated with the transformation of Znads is related to the reconfiguration of Znads during the nucleation of octahedral Zn layer structures. Furthermore, the primary process controlling Zn isotope fractionation is different under varying experimental conditions, leading to distinct Zn isotope fractionation between the bulk solid and solution during Zn–Fe coprecipitation. Low pH values (5.0–6.0) and initial Zn/Fe ratios (0.01–0.02) favor the direct precipitation of Znaq, resulting in slightly negative Zn isotope fractionation between the bulk solid and solution. In contrast, high pH values (7.0–7.5) and initial Zn/Fe ratios (0.1–0.2) favor surface complexation and the transformation of Znads, leading to heavy Zn isotope enrichment in the bulk solid. These findings offer novel insights into the primary mechanism through which Fe (hydr)oxides regulate Zn bioavailability in Zn-deficient soils and provide experimental evidence supporting the potential application of Zn isotopes as an indicator for comprehending the fate of Zn controlled by Fe (hydr)oxides in soils.

Case Studies of a Simulation Workflow to Improve Bone Healing Assessment in Impending Non-Unions.

Background: The healing potential of a fracture is determined by mechanical and biological factors. Simulation-based workflows can help assess these factors to assist in predicting non-unions. The aim of this study was the introduction of two use cases for a novel patient-specific simulation workflow based on clinically available information. Methods: The used software is an extension of the "Ulm Bone Healing model" and was applied in two cases with non-union development after fracture fixation to show its principal feasibility. The clinical and radiographic information, starting from initial treatment, were used to feed the simulation process. Results: The simulation predicted non-union development and axial deviation in a mechanically driven non-union. In the case of a biological non-union, a slow, incomplete healing course was correctly identified. However, the time offset in callus bridging was discordant between the simulation and the distinctly slower healing response in the clinical case. Conclusions: The simulation workflow presented in the two clinical use cases allowed for the identification of fractures at risk for impending non-union immediately after the initial fixation based on available clinical and radiographic information. Further validation in a large non-union cohort is needed to increase the model's precision, especially in biologically challenging cases, and show its validity as a screening instrument.

Midazolam versus Ondansetron versus Dexamethasone in Preventing Post-Operative Nausea and Vomiting after Elective Laparoscopic Abdominal Surgeries

Abstract Background Laparoscopic surgery is associated with a remarkably high risk of post-operative nausea and vomiting. The reasons for this high rate of PONV include mechanical factors (such as pressure on the stomach and gut caused by the pneumoperitoneum), neural factors (such as vagal reflexes elicited by irritation of parasympathetic nerve endings in the abdomen), and chemical factors (which include speculative considerations regarding a possible influence of CO2 on PONV). Objective To compare the effect of midazolam, ondansetron or dexamethasone on prophylaxis against PONV in patients undergoing laparoscopic abdominal surgeries. Patients and Methods After approval of anesthesiology department, scientific and ethical committees in Ain Shams University Hospitals, patients were included in the study, and were divided into three groups (n = 40; each); group M (midazolam group) and Group O (ondansetron group) and group D (dexamethasone group). Results The three groups were adequately monitored and assessed post-operatively and they were compared regarding post-operative nausea and vomiting outcome by recording the incidence of nausea and vomiting and recording the call for rescue antiemetic. Demographic data, intra-operative hemodynamics and post-operative pain score, occurrence of side effects, sedation score and patient satisfaction scores were also assessed, we found about 95% of (M) group achieve the complete response, that mean midazolam provided PONV prophylaxis comparable to dexamethasone and ondansetron in patients who underwent laparoscopic abdominal surgeries. Conclusion From this study, we can conclude that the midazolam is as effective as ondansetron and dexamethasone in reducing the incidence of nausea and vomiting in post-operative period of laparoscopic abdominal surgeries.

Composite error event-triggered-based finite-time safe formation control of underactuated vessels

For the problems of limited communication bandwidth and frequent triggering of actuators during the formation navigation, comprehensively considering the safety performance and coordinated control performance, a novel composite error event-triggered-based formation control strategy is proposed. Firstly, design an event-triggered-based finite-time extended state observer, which can not only quickly estimate the compound disturbances and velocity information simultaneously, but also reduce the communication frequency between sensor and observer. Secondly, considering the communication frequency and coordinated control performance of the whole formation system, a composite error based on the state information of adjacent underactuated vessels is defined, and it is used as a factor of the event-triggered mechanism. Then, by combining the exponential potential energy function, the composite error event-triggered-based formation controller is designed. And through stability analysis, we known that all signals of the system are uniformly ultimately bounded. Furthermore, the Zeno phenomenon that exists in event-triggered control can also be avoided completely. Finally, through simulation results and comparative analysis, the effectiveness of the composite error event-triggered-based formation control scheme for safe navigation control and reducing communication frequency and triggering frequency has been verified.

Mechanical stress-induced connective tissue growth factor plays a critical role in intestinal fibrosis in Crohn's-like colitis.

Crohn's disease (CD) is an inflammatory bowel disease characterized by transmural inflammation and intestinal fibrosis. Mechanisms of fibrosis in CD are not well understood. Transmural inflammation is associated with inflammatory cell infiltration, stenosis, and distention, which present mechanical stress (MS) to the bowel wall. We hypothesize that MS induces gene expression of profibrotic mediators such as connective tissue growth factor (CTGF), which may contribute to fibrosis in CD. A rodent model of CD was induced by intracolonic instillation of TNBS to the distal colon. TNBS instillation induced a localized transmural inflammation (site I), with a distended colon segment (site P) proximal to site I. We detected significant fibrosis and collagen content not only in site I but also in site P in CD rats by day 7. CTGF expression increased significantly in sites P and I, but not in the segment distal to the inflammation site. Increased CTGF expression was detected mainly in the smooth muscle cells (SMCs). When rats were fed exclusively with clear liquid diet to prevent mechanical distention in colitis, expression of CTGF in sites P and I was blocked. Direct stretch led to robust expression of CTGF in colonic SMC. Treatment of CD rats with anti-CTGF antibody FG-3149 reduced fibrosis and collagen content in both sites P and I and exhibited consistent trends toward normalizing expression of collagen mRNAs. In conclusion, our studies suggest that mechanical stress, by upregulating profibrotic mediators, i.e., CTGF, may play a critical role in fibrosis in CD.NEW & NOTEWORTHY We found that CTGF expression increased significantly not only in the inflammation site but in the distended segment proximal to inflammation in a rodent model of CD-like colitis. Release of mechanical distention prevented CTGF expression in CD rats, whereas direct stretch induced CTGF expression. Treatment with anti-CTGF antibody reduced fibrosis and collagen contents in CD rats. Thus, mechanical stress, via upregulating profibrotic mediators, i.e., CTGF, may play a critical role in fibrosis in CD.

Shari’ah governance and transparency: evidence from stock price synchronicity of Islamic banks

PurposeThe purpose of this study is to investigate internal governance mechanisms factors, focusing on Shari’ah-based governance mechanisms that affect the price synchronicity of Islamic banks (IBs).Design/methodology/approachThis study analyzes and compares the effect of Shari’ah and regular governance mechanisms on stock price synchronicity over 2013–2022 using a sample of 51 listed IBs in 13 countries in the Middle East and South Asia region. Using generalized least square method, this paper tests nine hypotheses addressing Shari’ah and regular governance mechanisms.FindingsThe findings generally reveal that Shari’ah-based governance mechanisms have a significant impact on the stock price synchronicity of IBs. The main determinants of stock price synchronicity among IBs are SSB size, SSB diversity, SSB members’ qualifications in finance Islamic jurisprudence and SSB interlocks. Shari’ah governance plays a detrimental role in improving the association between bank stock price synchronicity and transparency.Research limitations/implicationsThis paper includes three main limitations that may affect the accuracy of the findings. First, this paper relied on publicly available financial statements of IBs online. Hence, the data in this study is from few IBs in each country, which limits the analysis given the reliance is on the best-performing IBs in the country. Second, the results are restricted to the Middle East and South Asia and may not be generalized to other regions. Third, the sample is dominated by Middle East countries (i.e. 37 IBs out of 51).Practical implicationsBoth Shari’ah governance and regular governance have an impact on the transparency of IBs. Policymakers or regulators could encourage IBs to embed SSBs into their internal governance structure for the positive impact the SSBs attributes have on stock price synchronicity and transparency.Originality/valueThis research studies IBs, unlike most other works that focus on firms.

3D slope stability analysis considering strength anisotropy by a micro-structure tensor enhanced elasto-plastic finite element method

This article presents a micro-structure tensor enhanced elasto-plastic finite element (FE) method to address strength anisotropy in three-dimensional (3D) soil slope stability analysis. The gravity increase method (GIM) is employed to analyze the stability of 3D anisotropic soil slopes. The accuracy of the proposed method is first verified against the data in the literature. We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90° turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions. Based on our numerical results, the end effect significantly impacts the failure mechanism and safety factor. Anisotropy degree notably affects the safety factor, with higher degrees leading to deeper landslides. For concave slopes, they can be approximated by straight slopes with suitable boundary conditions to assess their stability. Furthermore, a case study of the Saint-Alban test embankment A in Quebec, Canada, is provided to demonstrate the applicability of the proposed FE model.

Rock Mass Characterization and Slope Stability Analysis Inlet Portal of Jragung Dam Diversion Tunnel, Indonesia

Abstract Slope stability is a serious problem that academics are still looking into in terms of human safety, equipment, and structures along the slope. Failure on slopes happens for a variety of reasons, including rock physical and mechanical properties, discontinuity factors, slope geometry, and external variables like as rainfall and seismic activity. The research location was conducted on the Jragung dam diversion tunnel, administratively located in Candirejo village, Pringapus sub-district, Semarang, Central Java Province. The purpose of this study was to use an empirical and numerical method to investigate the impact of rock mass categorisation on slope stability. The RMR (Rock mass rating) method is used to characterize rock mass, and the SMR (Slope mass rating) method is used to measure slope stability. The numerical slope stability analyses were carried out with the help of Phase2 (Rocscience, Inc.). The results showed that the slope at the intake portal was class IV (poor), and that it was unstable utilizing the SMR technique. According to numerical research, the basic design cut slopes with a 51° inclination were found to be unstable even after strengthening. It was suggested that the slope geometry and support measures be adjusted even more. Modified cut slopes were found to be stable after the slope inclinations were changed from 51° to 27° and shotcrete and rock bolt reinforcement were added.

Acute Pancreatitis after EGD: Case Presentation and Literature Review of this Rare Post-Procedure Complication.

Acute pancreatitis is a common cause of hospitalisation characterised by inflammation of the pancreas. While mechanical, toxic and iatrogenic factors typically cause it, post-oesophagogastroduodenoscopy (EGD) pancreatitis is extremely rare. This report examines a case of acute pancreatitis following EGD, aiming to highlight this rare but significant complication. A 46-year-old woman with a history of breast cancer, anxiety, vitamin D deficiency and gastro-oesophageal reflux disease underwent an EGD, which revealed and led to the removal of duodenal polyps. Six hours post-procedure, she presented with severe abdominal pain radiating to her back, accompanied by nausea. Laboratory results indicated elevated lipase levels, and a computed tomography (CT) scan confirmed acute pancreatitis. The patient was managed with aggressive fluid resuscitation, bowel rest and pain management, leading to an improvement in her condition and subsequent discharge. We believe that the pancreatitis was likely caused by the use of cautery during the endoscopic mucosal resection of duodenal polyps. This case underscores the need for clinicians to recognise acute pancreatitis as a potential complication of EGD, especially in the absence of other common risk factors. Acute pancreatitis following oesophagogastroduodenoscopy (EGD) is an uncommon but significant complication.Possible mechanisms include mechanical trauma, gas insufflation or electrical injury during endoscopic mucosal resection.Clinicians should be aware of this potential complication, especially when no typical aetiological factors for pancreatitis are present.

Vertical confinement enhances surface exploration in bacterial twitching motility.

Bacteria are often found in environments where space is limited, and they attach themselves to surfaces. One common form of movement on these surfaces is bacterial twitching motility, which is powered by the extension and retraction of type IV pili. Although twitching motility in unrestricted conditions has been extensively studied, the effects of spatial confinement on this behaviour are not well understood. In this study, we explored the diffusive properties of individual twitching Pseudomonas aeruginosa cells in spatially confined conditions. We achieved this by placing the bacteria between layers of agarose and glass, and then tracking the long-term twitching motility of individual cells. Interestingly, we found that while confinement reduced the immediate speed of twitching, it paradoxically increased diffusion. Through a combination of mechanical and geometrical analysis, as well as numerical simulations, we showed that this increase in diffusion could be attributed to mechanical factors. The constraint imposed by the agarose altered the diffusion pattern of the bacteria from normal to superdiffusion. These findings provide valuable insights into the motile behaviour of bacteria in confined environments.

Mengoptimalkan Analisis Sifat Mekanik Material Berbasis Data Dengan Pandas Profiling

The analysis of mechanical properties based on data is a method used to analyze the mechanical properties of a material using data, typically obtained from a material database. This process encounters several challenges, such as large volume of data, complexity in data processing, as well as difficulties in data visualization and interpretation. In this study, Pandas Profiling, a Python library designed specifically for automated dataset analysis, was employed. The dataset used consisted of tensile test results for various austenitic stainless steel types such as SUS 304, SUS 316, SUS 321, SUS 347, and NCF 800H. This dataset comprised 1916 samples with attributes related to mechanical properties and factors influencing them. The analysis results using Pandas Profiling indicated a strong negative correlation between heat treatment temperature and Yield Strength (YS) and Ultimate Tensile Strength (UTS). Additionally, a positive correlation was found between chemical elements such as Copper (Cu) and Nickel (Ni) with Elongation (EL). Furthermore, the analysis results revealed that stainless steel treated with water cooling exhibited a higher average UTS value, measuring at 493 MPa, compared to air cooling, which only reached 403 MPa. Pandas Profiling offers an effective solution to overcome common challenges in data-based mechanical property analysis, including dealing with large data volumes, complex data processing, as well as challenges in data visualization and interpretation. By utilizing Pandas Profiling, researchers can easily comprehend the dataset comprehensively, identify patterns, trends, and relationships among variables, and optimize the analysis process of data-based material mechanical properties.

4H silicon carbide bulk acoustic wave gyroscope with ultra-high Q-factor for on-chip inertial navigation

Inertial navigation on a chip has long been constrained by the noise and stability issues of micromechanical Coriolis gyroscopes, as silicon, the dominant material for microelectromechanical system devices, has reached the physical limits of its material properties. To address these challenges, this study explores silicon carbide, specifically its monocrystalline 4H polytype, as a substrate to improve gyroscope performance due to its low phonon Akhiezer dissipation and its isotropic hexagonal crystal lattice. We report on low-noise electrostatic acoustic resonant gyroscopes with mechanical quality factors exceeding several millions, fabricated on bonded 4H silicon carbide-on-insulator wafers. These gyroscopes operate using megahertz frequency bulk acoustic wave modes for large open-loop bandwidth and are tuned electrostatically using capacitive transducers created by wafer-level deep reactive ion etching. Experimental results show these gyroscopes achieve superior performance under various conditions and demonstrate higher quality factors at increased temperatures, enabling enhanced performance in an ovenized or high-temperature stabilized configuration.

Decoupling shear stress and pressure effects in the biomechanics of autosomal dominant polycystic kidney disease using a perfused kidney-on-chip.

Kidney tubular cells are submitted to two distinct mechanical forces generated by the urine flow: shear stress and hydrostatic pressure. In addition, the mechanical properties of the surrounding extracellular matrix modulate tubule deformation under constraints. These mechanical factors likely play a role in the pathophysiology of kidney diseases as exemplified by autosomal dominant polycystic kidney disease, in which pressure, flow and matrix stiffness have been proposed to modulate the cystic dilation of tubules with PKD1 mutations. The lack of in vitro systems recapitulating the mechanical environment of kidney tubules impedes our ability to dissect the role of these mechanical factors. Here we describe a perfused kidney-on-chip with tunable extracellular matrix mechanical properties and hydrodynamic constraints, that allows a decoupling of shear stress and flow. We used this system to dissect how these mechanical cues affect Pkd1 -/- tubule dilation. Our results show two distinct mechanisms leading to tubular dilation. For PCT cells (proximal tubule), overproliferation mechanically leads to tubular dilation, regardless of the mechanical context. For mIMCD-3 cells (collecting duct), tube dilation is associated with a squamous cell morphology but not with overproliferation and is highly sensitive to extracellular matrix properties and hydrodynamic constraints. Surprisingly, flow alone suppressed Pkd1 -/- mIMCD-3 tubule dilation observed in static conditions, while the addition of luminal pressure restored it. Our in vitro model emulating nephron geometrical and mechanical organization sheds light on the roles of mechanical constraints in ADPKD and demonstrates the importance of controlling intraluminal pressure in kidney tubule models.

Research on Occupational Risk Assessment for Welder Occupation in Romania

The ever-increasing needs of the working population have led to the development of various branches of industry, an increase in the number of employees, and a rise in the number of work-related accidents. The welder occupation is one of the most sought after occupations in Europe, according to the EURopean Employment Services (EURES) statistics. Taking into account the work system in which welders conduct their activity (uncomfortable working positions, splashes, high temperatures, mechanical factors, gases and fumes, magnetic fields due to electric current), the paper presents the risk factors identified for the welder occupation, based on the occupational injury and illness risk assessments. Following the analysis of 25 risk assessments, carried out by the assessment team that must include qualified evaluators, process specialists, the workers’ representative, occupational health and safety responsible at various industrial economic agents, a total of 70 main risk factors of occupational accidents and diseases were identified for the welder occupation. Risk factors were classified according to four main work components: worker, workload, work environment, and means of production. To reflect the importance of the identified risk factor, the number of organizations that considered that the risk was likely to occur but also the possibility that the risk was above the acceptable limit, calculated using the National Institute for Research and Development for Labor Protection “Alexandru Darabont” (INCDPM) method, a method often used in Romania, was identified from the analyzed assessments. Finally, a prevention and protection plan was drawn up with regard to the risks identified for the welder occupation, the final aim of which was to respectively reduce the probability of occurrence with the severity of the risks identified.

Quantum phase structural stability and switching in twist-graphenes

This study examines the electronic structure and potential energy surfaces of migration paths in various types of bilayer graphene. Using periodic boundary conditions, density functional theory (DFT), and the generalized gradient approximation (GGA) exchange–correlation functional, along with the nudged elastic band (NEB) method, to investigate the structural stability and dynamic equilibrium of twisted bilayer graphenes (TBGs) with twist angles of 13.2° and 21.8°. The results suggest that twist angles significantly impact atomic and electronic properties, including moiré patterns, superlattice periods, and interfragment distances, which in turn influence bilayer graphene strongly correlated electronic quantum states. This research elucidates the fundamental mechanisms of superlubricity and mutual migration pathways of graphene fragments in TBGs. The low migration barriers observed could facilitate transitions between different energy-related phases, which are determined by the lattice moiré patterns and the localization character of the electronic states, resulting in superlubricity. External mechanical factors may affect the quantum properties of TBGs, indicating potential applications in quantum computing and quantum sensing.

Dual role of dissolved black carbon in sensitized ofloxacin photooxidation: Mechanism and influential factors

Dissolved black carbon (DBC) is the more photoactive component of dissolved organic matter (DOM) pool, which plays a dual role in the photoconversion of aquatic contaminants, acting as both a photosensitizer and an inhibitor. However, little is known about the more systematic mechanism by which DBC exhibits a dual effect, which is closely related to the structure composition of DBC. In this study, the differences in characteristics of DBC obtained from 300 °C and 500 °C were compared via UV–vis absorption spectrum, Fluorescence excitation emission matrix spectra (3D-EEM), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS), and evaluated the promoting and inhibiting effects of DBC on ofloxacin (OFL) photodegradation. It was found that higher pyrolysis temperature reduced the UV absorbance, molecular weight, aromaticity, and phenolics of DBC while increasing the content of quinone/aromatic ketone and humic substances. Photochemical data showed that 3DBC*, 1O2 and ·OH were all participated in the DBC-mediated OFL photodegradation. Wherein, DBC300 (DBCT, where T = pyrolysis temperature) had strong light screening and dynamic quenching effect, but the formation ability of 3DBC*, 1O2 and ·OH was poor, which significantly retarded the photodegradation of OFL. While DBC500 exhibited a slight promotion effect due to its higher formation ability of reactive species and weak light screening effect. Moreover, DBC500 had higher steady-state concentration and (kOFL,3DBC⁎) than DBC300, which might be due to the higher contents of quinone/aromatic ketone and the lower contents of phenol in DBC500, thus enhancing the reactivity of 3DBC* and OFL. Our research systematically revealed the trade-off mechanism of DBC on the photodegradation of fluoroquinolones, and provided an important theoretical guidance for the photodegradation of fluoroquinolones under the evolution of DBC composition.

Elastomers based on polynorbornene with polar polysiloxane brushes for soft transducer applications

Elastomers based on cross‐linked bottlebrush polymers combine an extreme softness at low strains with a strain‐stiffening effect, which makes them attractive as active components in dielectric elastomer actuators (DEA). Their main disadvantage concerns the small relative permittivity, which lies in the range of 3.5, requiring relatively high driving voltage in actuators. We synthesized a bottlebrush polymeric elastomer with polar brushes, which exhibit an enhanced dielectric permittivity of 4.4. Anionic ring‐opening polymerization of a polar cyclosiloxane afforded telechelic polar brushes, while ring‐opening polymerization of a norbornene macromonomer gave a bottlebrush polymer which was cross‐linked to elastomers by a thiol‐ene reaction. Elastomers with a small elastic modulus below 100 kPa, strain at break exceeding 100%, attractive elasticity, and small mechanical loss factors (tanδ) were achieved. Temperature‐dependent impedance measurements revealed a transition temperature of ‐95 °C and an interfacial polarization. The multigram scale synthesis demonstrates the potential for scaling up, which opens the door to broader applications of these materials beyond actuators, such as capacitive sensors, batteries, and electroluminescent devices. Notably, these devices operate at extremely low voltages where the dielectric breakdown does not limit their functionality, but still, the softness and the increased dielectric permittivity are a plus.

Relationship between mechanical behavior and process factors in friction stir welding aluminum alloys

The friction stir welding (FSW) procedure is the main topic of this research study among the various welding techniques. The study focuses on the interaction between the mechanical properties of 3003 aluminum alloy and the process parameters (rotation speed, welding speed, and dwell time) in the form of rolled plates of 2 mm thickness, end-to-end and welded at 90° and 45°. The welds were made by varying the speed of rotation (1000, 2000 rpm) and setting the tool feed at 500 mm/min. This experimental approach is also based on varying the tilt of the welding tool from 0° to 2°. It has been shown that the studied parameters play an important role in the characterization and optimization of the above mentioned weld joints. Therefore, and based on the results obtained, the use of the 90° joint remains the best in terms of strength.