Search Results (298)

A series of polyether and poly(ether carbonate) polyols have been synthesized via Zn(II)-Co(III) double metal cyanide (DMC)-catalyzed ring-opening (co)polymerization of various epoxides, such as propylene oxide, 1,2-epoxybutane, epichlorohydrin, styrene oxide, and glycidol, with and without CO₂. The resulting polyether polyols exhibit linear and branched architectures (degrees of branching, DB = 0.27), high catalytic activities with turnover frequencies up to 461 min⁻¹, narrow dispersities (1.15–1.25), and low levels of unsaturation (0.004 meq g⁻¹). The DMC catalysts also enable the efficient synthesis of poly(propylene carbonate) polyol with carbonate contents up to 40% and yields reaching 63%. Additionally, branched poly(ether carbonate) polyols with tunable DB values (0.14–0.21), yields up to 70%, and carbonate contents up to 33% are synthesized via CO₂ fixation to glycidol. The synthesized polyols hold strong potential for industrial applications in polyurethanes and other advanced materials, offering versatile performance for use in coatings, adhesives, sealants, and elastomers. Overall, this study highlights the effectiveness of DMC catalysts in producing high-performance polyols, contributing to the development of sustainable materials with precise architectural control. Full article

The sealing performance of ultra-high-pressure solenoid valves faces significant challenges, particularly under low-temperature conditions. Due to the difference in thermal expansion coefficients between the valve seat and the sealing tube, combined with material contraction at low temperatures, the bolt preload decreases, and consequently the contact force on the sealing surface and the average sealing specific pressure are reduced. This may result in an average sealing specific pressure falling below the required sealing specific pressure, causing leakage and failure of the ultra-high-pressure solenoid valve. To address this problem, this study utilizes theoretical and simulation analysis to examine the preload status in low-temperature environments and the causes of sealing failure in ultra-high-pressure solenoid valves. A corresponding optimization scheme is proposed, which involves increasing the torque from 120 N·m to 130 N·m and applying sealant to the threaded connection to enhance the sealing performance of the ultra-high-pressure solenoid valve. Following the increase in tightening torque and the application of thread sealant, the helium leakage rate at −40 °C is significantly reduced. Specifically, at a test pressure of 87.5 MPa, the helium leakage rate decreases from $1.6\times {10}^{-5}$ mbar·L/s to approximately $1.4\times {10}^{-6}$ mbar·L/s. At test pressures of 1.4 MPa and 10 MPa, the leakage rate is approximately $3.0\times {10}^{-7}$ mbar·L/s. Experimental verification shows that the proposed solution can significantly enhance the sealing reliability of ultra-high-pressure solenoid valves under extreme operating conditions. Full article

Post-operative pancreatic fistula (POPF) is a serious yet far too common complication following distal pancreatectomy (DP), as it affects 20–30% of patients after DP. POPF raises the risk of other complications and causes delays to a patient’s oncologic care. In this review, we present the latest data on patient risk factors for developing POPF, such as obesity, smoking, young age, thick pancreas, lack of epidural anesthesia, hypoalbuminemia, and elevated drain amylase levels. Other risk factors that have been identified with irregular consistency include open surgical approach, non-malignant or neuroendocrine tumor pathology, simultaneous splenectomy, simultaneous vascular resection, and long operative time. We also review the consequences of POPF, which include hemorrhage, infection, delayed gastric emptying, re-operation, re-admission, delays in adjuvant chemotherapy initiation, reduced progression-free survival, and reduced overall survival. Finally, we present strategies that have been studied for avoiding POPF after DP, including reducing pressure at the sphincter of Oddi, the use of sealants and patches, optimizing pancreatic transection, strategies for post-operative drain placement, the use of post-operative somatostatin analogues, and pre-clinical studies of experimental devices and techniques that may inform future trials. This review informs readers on the current state of the art with regard to POPF after DP and sets the stage for future studies to improve patient outcomes. Full article

This article investigates the acoustic properties of artificial discontinuities in reference specimens for the ultrasonic testing of welded joints in polyethylene pipes. An analysis is conducted on the reflectivity of various materials (air, sand, heat-resistant silicate-based sealant, and aluminum foil) and their correspondence to real defects occurring in weld seams. A theoretical analysis of reflection coefficients is performed, along with laboratory studies using digital radiography and ultrasonic testing. The results demonstrate that heat-resistant silicate sealant is the most suitable material for simulating defects, as its acoustic properties closely match those of real inclusions, and its geometric parameters remain stable during the welding process. The use of such specimens enhances the reliability of ultrasonic testing and reduces the likelihood of errors in defect classification. Full article

Asphalt pavement cracking represents a prevalent form of deterioration that significantly compromises road performance and safety under the combined effects of environmental factors and traffic loading. Crack sealing has emerged as a widely adopted and cost-effective preventive maintenance strategy that restores the pavement’s structural integrity and extends service life. This paper presents a systematic review of the development of crack sealing technology, conducts a comparative analysis of conventional sealing materials (including emulsified asphalt, hot-applied asphalt, polymer-modified asphalt, and rubber-modified asphalt), and examines the existing performance evaluation methodologies. Critical failure mechanisms are thoroughly investigated, including interfacial bond failure resulting from construction defects, material aging and degradation, hydrodynamic scouring effects, and thermal cycling impacts. Additionally, this review examines advanced sensing methodologies for detecting premature sealant failure, encompassing both non-destructive testing techniques and active sensing technologies utilizing intelligent crack sealing materials with embedded monitoring capabilities. Based on current research gaps, this paper identifies future research directions to guide the development of intelligent and sustainable asphalt pavement crack repair technologies. The proposed research framework provides valuable insights for researchers and practitioners seeking to improve the long-term effectiveness of pavement maintenance strategies. Full article

Axillary lymph node dissection (ALND), although increasingly less necessary, is still required in specific breast cancer surgery scenarios, such as cases with a high axillary tumor burden. However, traditional practices are being reassessed due to the associated morbidity and impacts on recovery. This review explores five critical and controversial innovations in ALND: (1) same-day discharge, (2) omission of surgical drains, (3) application of fibrin sealants, (4) minimally invasive techniques, and (5) their collective influence on quality of life (QoL). Same-day discharge has proven to be safe and cost-effective, increasing patient satisfaction without raising complication rates. The omission of drains, while slightly increasing seroma volumes, is linked to shorter hospital stays and fewer complications. The use of fibrin sealants shows promising results in reducing the seroma volume and duration, expediting recovery, although their routine use remains under debate. Minimally invasive and endoscopic techniques reduce morbidity and improve cosmetic outcomes while maintaining oncological safety. Quality of life (QoL) is essential in the evaluation of breast cancer treatment and is evaluated using tools such as EORTC QLQ-C30, QLQ-BR23, and FACT-B, SF-36, which assess physical, emotional, and psychosocial recovery. Innovations in ALND seem to improve QoL by minimizing pain, increasing arm function, and reducing psychological stress, underscoring the importance of patient-centered strategies. Although axillary lymphadenectomy increases arm morbidity compared to sentinel node biopsy, its overall impact on quality of life appears limited, likely due to the overlapping effects of systemic therapies and breast surgery. Full article

In recent decades, Blanket Dry Cow Therapy (BDCT) has been regarded as a cornerstone strategy for the control of mastitis in dairy cows during the dry period. However, concerns regarding the rising incidence of antibiotic resistance and the associated zoonotic risks have prompted a paradigm shift, leading to intensified research into alternative management approaches. In response, many countries have adopted a more targeted approach, known as Selective Dry Cow Therapy (SDCT), which focuses on the therapeutic use of antibiotics, administered only to cows or quarters that are either infected or at high risk of infection during the dry period. This review provides a comprehensive synthesis of the scientific literature regarding the main methods for selecting animals for SDCT, the impact of this strategy on udder health, milk production, farm economics, and antibiotic consumption, as well as the factors that may influence its effectiveness. Over time, a range of methods have been developed to identify infected animals, including bacteriological culture, somatic cell count (SCC), differential somatic cell count (DSCC), and the California Mastitis Test (CMT), which are often used alone or in combination with clinical mastitis history and/or parity. Among these methods, SCC has proven to be the most economically viable and best suited for practical use, while its combination with DSCC has been shown to significantly enhance diagnostic accuracy. According to the studies reviewed, SDCT is a safe and effective strategy for maintaining udder health and farm profitability, as long as infected cows are accurately identified, and internal teat sealants are used in quarters not treated with antibiotics during the dry period. However, since udder health is influenced by herd characteristics, management practices, and regional pathogens, the findings cannot be universally applied and must be adapted to each herd’s specific conditions. Full article

To assess structural sealant damage in hidden frame glass curtain walls (HFGCWs) during service, damage states were simulated by controlled cutting with varying incision lengths. Quantitative identification challenges were investigated through natural frequency and curvature modal difference (CMD) analyses at multiple test points. The results indicate that natural frequency decreases with increasing damage severity, while the first-order curvature mode difference (FCMD) exhibits localized abrupt changes in damaged regions. Boundary modes provide more targeted and accurate damage identification. The peak value of the FCMD mutation region enables precise damage localization. A quantitative damage identification threshold of 0.1205 was derived from FCMD distribution characteristics in boundary regions. By leveraging boundary mode features, modal testing efficiency is optimized, reducing the required acquisition nodes and effectively guiding structural sealant damage detection in engineering applications. Full article

Polybutadiene (PB) and polyisoprene (PI) rubbers are indispensable synthetic elastomeric materials widely used in tires, footwear, hose, belts, sealants, electricity, construction, and other applications. Nowadays, PB and PI elastomers are produced from butadiene (BD) and isoprene (IP) monomers via transition-metal-mediated coordination polymerization. Transition metal catalytic systems consist of a precise characteristic structural unit at the molecular level: well known as “single-site catalysts” (SSCs). These have experienced a revolutionary advance in the recently developed conjugated dienes synthetic rubber method. Among the SSCs, a class of rare-earth, metal-centered half-sandwich molecule has been identified as a high-performance catalytic system for conjugated dienes polymerization. These novel half-sandwich rare-earth (HSRE) catalytic systems exhibit several irreplaceable advantages compared with the conventional Ziegler–Natta-type catalytic systems. These HSRE catalytic systems can create novel conjugated diene rubbers (CDRs) with high catalytic reactivity, high stereoselectivity, an adjustable polymer chain microstructure, and high molecular weights and are considered to be the next generation of ecofriendly and economic catalytic systems for industrial applications. This paper delivers a concise review of some important synthetic methods for representative HSRE complexes with characteristic structures and of the utilization of some HSRE catalytic systems for the preparation of high-performance CDRs, especially highly stereoregular PI and PB materials. Full article

Fibrin sealants have been implemented in the management of burn wounds. They can be used either in combination with skin grafts for full-thickness burns or alone for treating superficial and deep dermal burns. The aim of this review was to provide critical insights regarding the efficacy of fibrin sealants in enhancing wound healing, improving graft adherence, and reducing complications. Therefore, evidence from experimental models and clinical trials was synthesized, underscoring the transformative role of fibrin sealants in modern burn care. This comprehensive review includes recent evidence on the potential benefits of fibrin sealants in the management of superficial and deep dermal or full-thickness burn injuries. Clinical and experimental evidence underscores some benefits in utilizing fibrin sealants in the management of superficial and deep dermal burn injuries, or in combination with skin grafts in full-thickness burns. Furthermore, fibrin sealants diminish postoperative pain and facilitate quick recovery for daily activities; however, controversy regarding their cost still remains. This review concludes that fibrin sealants could serve as a safe and effective therapeutic option for burn wound management. The safety and efficacy of their utilization, along with their wide availability and easiness to use, could make them an alternative treatment choice when a specialized plastic surgery service is not available, or in the emergency setting across different healthcare systems. Full article

Lignin, an abundant and renewable biopolymer, has gained significant attention as a sustainable modifier and building block in polymeric materials. Recent advancements highlight its potential to tailor mechanical, thermal, and barrier properties of polymers while offering a greener alternative to petroleum-based additives. This review provides an updated perspective on the incorporation of lignin into various polymer matrices, focusing on lignin modification techniques, structure–property relationships, and emerging applications. Special emphasis is given to recent innovations in lignin functionalization and its role in developing high-performance, biodegradable, and recyclable materials such as polyurethanes, epoxy resins, phenol-formaldehyde resins, lignin-modified composites, and lignin-based films, coatings, elastomers, and adhesives. These lignin-based materials are gaining attention for potential applications in construction, automated industries, packaging, textiles, wastewater treatment, footwear, supporting goods, automobiles, printing rollers, sealants, and binders. Full article

Crack sealant is commonly used to fill pavement cracks and improve the Pavement Condition Index (PCI). However, during asphalt pavement hot in-place recycling (HIR), irregular shapes and random distribution of crack sealants can cause issues like agglomeration and ignition. To address these problems, it is necessary to mill large areas containing crack sealant or pre-mark locations for removal after heating. Currently, detecting and recording crack sealant locations, types, and distributions is conducted manually, which significantly reduces efficiency. While deep learning-based object detection has been widely applied to distress detection, crack sealants present unique challenges. They often appear as wide black patches that overlap with cracks and potholes, and complex background noise further complicates detection. Additionally, no dataset specifically for crack sealant detection currently exists. To overcome these challenges, this paper presents a specialized dataset created from 1983 pavement images. A deep learning detection algorithm named YOLO-CS (You Only Look Once Crack Sealant) is proposed. This algorithm integrates the RepViT (Representation Learning with Visual Tokens) network to reduce computational complexity while capturing the global context of images. Furthermore, the DRBNCSPELAN (Dilated Reparam Block with Cross-Stage Partial and Efficient Layer Aggregation Networks) module is introduced to ensure efficient information flow, and a lightweight shared convolution (LSC) detection head is developed. The results demonstrate that YOLO-CS outperforms other algorithms, achieving a precision of 88.4%, a recall of 84.2%, and an mAP (mean average precision) of 92.1%. Moreover, YOLO-CS significantly reduces parameters and memory consumption. Integrating Artificial Intelligence-based algorithms into HIR significantly enhances construction efficiency. Full article

Sealing treatment is widely used as a simple and low-cost process to improve the long-term corrosion resistance of Fe-based amorphous coatings. In this study, an eco-friendly graphene modified waterborne acrylic sealant(WFS) with strong permeability was prepared by emulsion polymerization and GO@SiO₂ was introduced as a reinforcing material to increase the withstand resistance of the hybrid sealant to Cl⁻. A combination of ultrasonic excitation and vacuum sealing effectively promotes the penetration of the waterborne hybrid sealant into the pores of the coating. A 3D X-ray scan confirmed the sealant penetration depth of 160 μm. The natural properties of the emulsion were characterized by a particle size analyzer, FTIR, TGA-DSC and TEM. Potentiodynamic polarization curves and AC impedance spectroscopy analysis showed that GO@SiO₂ has a strong blocking ability to Cl⁻, which greatly promotes the integrity of the passive film. It is anticipated that the novel eco-friendly waterborne hybrid sealants with strong permeability will find applications in a variety of porous hard coatings. Full article

Background: This study aimed to analyze and compare the translucency and marginal adaptation of five resin-based materials used as occlusal sealants, both before and after simultaneous fatigue and thermocycling. Two null hypotheses were tested: (1) All tested materials allow the transillumination of sealed occlusal carious lesions. (2) There are no differences in marginal adaptation before and after simultaneous fatigue and thermocycling. Methods: Forty extracted human molars with early occlusal caries lesions were randomly divided into five equal groups. Near-infrared transillumination images of cleaned occlusal surfaces were captured before and after applying the following sealants: (I) OptiBond FL (adhesive alone), (II) OptiBond FL (primer and adhesive) (Kerr Corp., Brea, CA, USA), (III) Scotchbond Universal (3M, St. Paul, MN, USA) combined with OptiBond FL adhesive, (IV) Fissurit (VOCO GmbH, Cuxhaven, Germany), (V) Helioseal Clear (Ivoclar Vivadent AG, Schaan, Liechtenstein). A scanning electron microscope was used to assess marginal adaptation before and after simultaneous fatigue and thermocycling. The percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (Shapiro–Wilk Normality test, two-way ANOVA with Fisher’s post hoc test). Results: Helioseal Clear and Fissurit were fully transparent under near-infrared transillumination. The percentage of closed margins significantly decreased after loading in one group: OptiBond FL primer application before adhesive application significantly reduced marginal adaptation. Conclusion: OptiBond FL (adhesive), Scotchbond Universal with OptiBond FL (adhesive), Fissurit, and Helioseal Clear provided excellent marginal adaptation. However, using OptiBond FL primer on enamel negatively impacted adaptation. Helioseal Clear and Fissurit, as transparent sealants, may allow lesion monitoring using an 850 nm transillumination camera. Full article

Effective local hemostasis is essential in oral surgery to prevent complications such as delayed healing, infection, and the need for re-intervention. Postoperative bleeding occurs in 4–6% of cases, increasing to 9–12% in patients receiving anticoagulant or antiplatelet therapy. This review evaluates the efficacy, safety, and clinical utility of local hemostatic agents based on 51 studies published between 1990 and 2023. Traditional agents, such as oxidized cellulose and gelatin sponges, control bleeding in over 85% of standard cases but offer limited regenerative benefits. Autologous platelet concentrates (APCs), including platelet-rich plasma (PRP) and leukocyte- and platelet-rich fibrin (L-PRF), reduce bleeding time by 30–50% and enhance soft tissue healing. Studies show the PRP may reduce postoperative bleeding in dental surgery by 30–50%, and in orthopedic and cardiac surgery by 10–30%, particularly in patients on anticoagulants. Tranexamic Acid mouthwash can reduce postoperative bleeding by up to 50–60%. Fibrin sealants achieve a 70–90% reduction in bleeding among high-risk patients, while topical tranexamic acid decreases hemorrhagic events by up to 80% in anticoagulated individuals without increasing thromboembolic risk. However, comparative studies remain limited, particularly in medically compromised populations. Additional gaps persist regarding long-term outcomes, cost-effectiveness, and the standardized use of emerging agents such as nanomaterials. Future research should prioritize high-quality trials across diverse patient groups and develop clinical guidelines that integrate both safety and regenerative outcomes. Full article