Repair System Research Articles

Application of bandage repair systems in the power sector to restore pipeline integrity

This work explores the possibility of repairing damaged pressure piping systems using composite repair bandaging technology. Loctite technology from Henkel was selected from several existing methods and applied at the weld joint. To assess the performance of the bandage, a bore was made at the weld joint to simulate a replacement defect of the composite bandage. The bandage, along with the welded joints, was subjected to microstructural and macrostructural analysis, and mechanical and fire resistance tests were also performed. Based on the obtained results, it is concluded that the properties of the Loctite composite system are suitable for repairing pressure piping in the power industry. However, it is not always possible to use this repair method due to certain boundary conditions for its application, such as maximum pipe overpressure, the temperature of the internal medium and the environment, degradation of the repair system due to the medium being transferred and the environment, reduction of the pipe wall at the repair site, possible surface treatment before application of the system, etc. For these reasons, the repair system may be used for a temporary period (approved by the power plant operator), and the spot will then be repaired in the standard way by replacing parts of the pipeline during a planned equipment shutdown.

Oxidized sodium alginate hydrogel-mouse nerve growth factor sustained release system promotes repair of peripheral nerve injury

In recent years, mouse nerve growth factor (mNGF) has emerged as an important biological regulator to repair peripheral nerve injury, but its systemic application is restricted by low efficiency and large dosage requirement. These limitations prompted us to search for biomaterials that can be locally loaded. Oxidized sodium alginate hydrogel (OSA) exhibits good biocompatibility and physicochemical properties, and can be loaded with drugs to construct a sustained-release system that can act locally on nerve injury. Here, we constructed a sustained-release system of OSA-mouse nerve growth factor (mNGF), and investigated the loading and release of the drug through Fourier transform infrared spectroscopy and drug release curves. In vitro and in vivo experiments showed that OSA-mNGF significantly promoted the biological activities of RSC-96 cells and facilitated the recovery from sciatic nerve crush injury in rats. This observation may be attributed to the additive effect of OSA on promoting Schwann cell biological activities or its synergistic effect of cross-activating phosphoinositide 3-kinase (PI3K) through extracellular signal regulated kinase (ERK) signaling. Although the specific mechanism of OSA action needs to be explored in the future, the current results provide a valuable preliminary research basis for the clinical application of the OSA-mNGF sustained-release system for nerve repair.

Initial experience of a single surgeon for safety and feasibility of the Versius Robotic System in robot-assisted cholecystectomy and hernia repair.

This study aimed to evaluate the feasibility, safety, and perioperative outcomes of cholecystectomy and hernia repair performed with the Versius Robotic System by a surgeon with no prior robotic surgery experience. A retrospective analysis was conducted on adult patients who underwent cholecystectomy, inguinal, or umbilical hernia repair using the Versius Robotic System between August 2021 and June 2023 et al. Zahra Hospital, Dubai, UAE. A total of 105 patients (mean age 38.9 ± 9.2years) were included. Significant correlations existed between the number of robot-assisted cholecystectomies and the operative metrics. As the number increased, the duration of the total operative (r = -0.755, p < 0.001), docking (r = -0.683, p < 0.001), and console (r = -0.711, p < 0.001) times decreased, indicating improved efficiency with experience. This study demonstrates the safety and feasibility of the Versius Robotic System for cholecystectomy and hernia repair, even for surgeons lacking prior robotic surgery experience.

An experimental and parametrical study on repair of cracked titanium airframe structures with single-side bonded carbon fiber-reinforced polymer prepreg patches

The present research aims to investigate efficient repair techniques of cracked Ti-alloy aircraft structures with adhesively bonded carbon fiber-reinforced polymer prepreg patches. The repaired specimens in the configuration of a Ti-alloy butt joint with one-side bonded composite patch were prepared under multiple repair factors including patch thickness, patch length, adhesive thickness, cure pressure, patch layup and surface treatment. The repair efficiency was evaluated by loading behavior, bonded interface microstructure and failure mode. The results reveals that the geometric factors affect the loading performance and alter failure modes by adjusting stress distribution in the repair system, whereas the cure pressure and surface treatment act on the bondline and change interfacial properties. A sensitivity-optimization model based on analysis of variance was established for parametrical study to quantify the contribution of repair factors and obtain optimal values. The optimum parameters were validated by repaired central-cracked specimens via static and fatigue tests, which proved that the repaired structure could restore 90.7% loading capacity of intact ones and endure more than 106 fatigue cycles of 25% ultimate failure load level of center-cracked ones. The proposed experimental and parametrical study possessed good efficacy in refurbishing strength and stiffness of cracked metallic structures.

Pathogenic variants in human DNA damage repair genes mostly arose in recent human history.

Genome stability is maintained by the DNA damage repair (DDR) system composed of multiple DNA repair pathways of hundreds of genes. Germline pathogenic variation (PV) in DDR genesdamages function of the affected DDR genes, leading to genome instability and high risk of diseases, in particular, cancer. Knowing evolutionary origin of the PVs inhuman DDR genes is essential to understand the etiology of human diseases. However, answer to the issue remains largely elusive. In this study, we analyzed evolutionary origin for the PVs inhuman DDR genes. We identified 169 DDR genes by referring tovarious databases and identified PVs in theDDR genes of modern humans from ClinVar database. We performed a phylogenetic analysis to analyze the conservation of human DDR PVs in 100 vertebrates through cross-species genomic data comparison using the phyloFit program of the PHAST package and visualized the resultsusing theGraphPad Prism software and the ggplot module. We identified DDR PVs from over 5000ancient humansdeveloped a database to host the DDR PVs ( https://genemutation.fhs.um.edu.mo/dbDDR-AncientHumans ). Using the PV data,we performed a molecular archeological analysis tocompare theDDR PVs between modern humans and ancient humans. We analyzed evolution selection of DDR genes across 20 vertebrates using theCodeML in PAML for phylogenetic analysis. Ourphylogenic analysis ruled out cross-species conservation as the origin of human DDR PVs. Ourarcheological approach identified rich DDR PVs shared between modern and ancient humans, which were mostly dated within the last 5000 years. We alsoobserved similar pattern of quantitative PV distribution between modern and ancient humans. We furtherdetected a setof ATM, BRCA2 and CHEK2 PVs shared between human and Neanderthals. Our study reveals that human DDR PVs mostly arose in recent human history. We propose that human high cancer risk caused by DDR PVs can be a by-product of human evolution.

An integrated framework of preventive maintenance and task scheduling for repairable multi-unit systems

Preventive maintenance and task scheduling are both crucial activities in industrial practice. Although they are interdependent and mutually influential, most existing studies typically analyze them separately. In this paper, an integrated framework of preventive maintenance planning and task scheduling is explored. On one hand, while most scholars focus on the system as a whole in scheduling studies, we further take into account the degradation and maintenance of multiple units during the task scheduling process. On the other hand, instead of only using "direct replacement" as the main maintenance method, we further consider the repairability of the unit by incorporating imperfect maintenance effects into the maintenance modeling. Additionally, the lifecycle partitioning method is proposed to analyze the maintenance groups for multiple units at the completion of scheduling tasks and their corresponding probabilities. Based on this foundation, an integrated decision model is established with the preventive maintenance threshold and scheduling task sequence as decision variables to minimize the total weighted expected completion time. Finally, a novel genetic algorithm based on hybrid encoding is proposed, and the effectiveness of integrated decision-making was validated using a practical example.

Clinical aspects and treatment of tricuspid valve regurgitation

Tricuspid regurgitation (TR) leading to right heart failure is prevalent and associated with increased mortality. The significant under-recognition of the disease resulted from insufficient medical therapies and the high associated risk of surgical therapy. Over the last decade there has been a rapid development of interventional treatment options so that the disease has increasingly become the focus of attention of specialists in internal medicine and interventional cardiologists. The etiology of TR is differentiated into primary TR, secondary atrial TR, secondary ventricular TR and TR associated with cardiac implantable electronic devices (CIED). The TR was identified as an independent predictor of mortality, independent of associated diseases such as atrial fibrillation, left-sided heart failure or pulmonary hypertension. Even patients with low to moderate TR have asignificantly increased risk of mortality. Early diagnostics and estimation of the severity by echocardiography as well as timely referral to atertiary heart valve center are decisive in order to evaluate possible treatment options before irreversible right ventricular damage and secondary organ dysfunction occur. For transcatheter edge-to-edge repair and transcatheter tricuspid valve replacement there is now first evidence from randomized controlled studies. While the understanding of TR is continuously improving, new tricuspid valve repair and replacement systems are in a state of steady progress. Whether the treatment has an effect on reduction of the mortality and stabilization of right ventricular failure with a reduction in hospitalization, will first be shown in future studies.

Injectable, self-healing hydrogels based on gelatin, quaternized chitosan, and laponite as localized celecoxib delivery system for nucleus pulpous repair

Utilization of injectable hydrogels stands as a paradigm of minimally invasive intervention in the context of intervertebral disc degeneration treatment. Restoration of nucleus pulposus (NP) function exerts a profound influence in alleviating back pain. This study introduces an innovative class of injectable shear-thinning hydrogels, founded on quaternized chitosan (QCS), gelatin (GEL), and laponite (LAP) with the capacity for sustained release of the anti-inflammatory drug, celecoxib (CLX). First, synthesis of Magnesium-Aluminum-Layered double hydroxide (LDH) was achieved through a co-precipitation methodology, as a carrier for celecoxib and a source of Mg ions. Intercalation of celecoxib within LDH layers (LDH-CLX) was verified through a battery of analytical techniques, including FTIR, XRD, SEM, EDAX, TGA and UV–visible spectroscopy confirmed a drug loading efficiency of 39.22 ± 0.09 % within LDH. Then, LDH-CLX was loaded in the optimal GEL-QCS-LAP hydrogel under physiological conditions. Release behavior (15 days profile), mechanical properties, swelling ratio, and degradation rate of the resulting composite were evaluated. A G* of 15–47 kPa was recorded for the hydrogel at 22–40 °C, indicating gel stability in this temperature range. Self-healing properties and injectability of the composite were proved by rheological measurements. Also, ex vivo injection into intervertebral disc of sheep, evidenced in situ forming and NP cavity filling behavior of the hydrogel. Support of GEL-QCS-LAP/LDH-CLX (containing mg2+ ions) for viability and proliferation (from ~94 % on day 1 to ~134 % on day 7) of NP cells proved using MTT assay, DAPI and Live/Dead assays. The hydrogel could significantly upregulate secretion of glycosaminoglycan (GAG, from 4.68 ± 0.1 to 27.54 ± 1.0 μg/ml), when LHD-CLX3% was loaded. We conclude that presence of mg2+ ion and celecoxib in the hydrogel can lead to creation of a suitable environment that encourages GAG secretion. In conclusion, the formulated hydrogel holds promise as a minimally invasive candidate for degenerative disc repair.

Genetic variations in DNA excision repair pathway contribute to the chemosensitivity and prognosis of acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy with a high recurrence rate and poor long-term prognosis. DNA excision repair systems, such as base excision repair (BER) and nucleotide excision repair (NER), play a major role in maintaining genomic stability and integrity. Further intensive investigations are necessary to uncover additional AML prognosis loci. In this study, we analyzed 16 candidate SNPs within NER and BER pathways in AML patients. Our results showed the GT/GG genotype of the XPC rs2228001 polymorphism was significantly associated with WBC count in dominant models (OR = 0.41, 95 % CI = 0.18–0.96, p = 0.039). Additionally, the rs25487 and rs3213245 SNPs in the XRCC1 gene, in both co-dominant and dominant models, were significantly associated with PLT count in AML (p < 0.05). The GG genotype of rs1130409 in APEX1 was more prone to adverse cytogenetics in both the codominant and recessive models (p < 0.05). Furthermore, the GA genotypes of ERCC8 rs158572 in codominant model was significantly correlated with refractory group (p < 0.05). ERCC8 rs158572 and XRCC1 rs3213245 in both codominant and dominant models were significantly correlated with the MRD positivity (p < 0.05). Kaplan-Meier analysis revealed an link between overall survival (OS) and the co-dominant, dominant, and recessive models of rs2228001 in XPC. Additionally, patients with the GG and GT/GG genotype in the co-dominant, dominant model and recessive model in XPC rs2228001 exhibited significantly longer survival (p < 0.05). Multivariate Cox analyses indicated that rs2228001 in both co-dominant and dominant models were independent favorable factors impacting patient OS (OR < 1). Our findings suggest that genetic polymorphisms in DNA excision repair pathway genetic polymorphisms contribute to the chemosensitivity and prognosis of acute myeloid leukemia.

Differential impacts of DNA repair machinery on fluoroquinolone persisters with different chromosome abundances.

Persisters are rare phenotypic variants in isogenic populations that survive antibiotic treatments that kill the other cells present. Evidence has accumulated that supports a role for persisters in chronic and recurrent infections. Here, we explore how an under-appreciated phenotypic variable, chromosome copy number (#Chr), influences the DNA repair systems persisters use to survive fluoroquinolone treatments. We found that #Chr significantly biases the DNA repair systems used by persisters, which suggests that #Chr heterogeneity should be considered when devising strategies to eradicate these troublesome bacterial variants.

Updated Estimates of Radiation Risk for Cancer and Cardiovascular Disease: Implications for Cardiology Practice.

This review aims to furnish an updated assessment of the societal healthcare load, including cancer and cardiovascular disease resulting from diagnostic radiologic operations. The previously projected additional cancer risk of 0.9% in a United States 2004 study referred to radiological conditions in 1996 with an X-ray exposure of 0.50 millisievert (mSv) per capita annually. Radiological exposure (radiology + nuclear medicine) has escalated to 2.29 mSv (2016) per capita per year. Low-dose exposures were previously assumed to have a lower biological impact, since they allow the DNA repair system to mitigate molecular damage. However, epidemiological data matured and disproved this assumption, as shown by updated cancer risk assessments derived from the World Health Organization 2013 and the German Institute of Radioprotection 2014 data. The risk of cardiovascular disease aligns within the same order of magnitude as cancer risk and compounds it, as shown by a comprehensive meta-analysis of 93 studies. The collective societal burden arising from the augmented risks of cancer and cardiovascular disease attributable to diagnostic radiology and nuclear medicine is higher than previously thought.

A complexity evaluation system for mitral valve repair based on preoperative echocardiographic and machine learning

BackgroundTo develop a novel complexity evaluation system for mitral valve repair based on preoperative echocardiographic data and multiple machine learning algorithms. MethodsFrom March 2021 to March 2023, 231 consecutive patients underwent mitral valve repair. Clinical and echocardiographic data were included in the analysis. The end points included immediate mitral valve repair failure (mitral replacement secondary to mitral repair failure) and recurrence regurgitation (moderate or greater mitral regurgitation [MR] before discharge). Various machine learning algorithms were used to establish the complexity evaluation system. ResultsA total of 231 patients were included in this study; the median ejection fraction was 66% (63–70%), and 159 (68.8%) patients were men. Mitral repair was successful in 90.9% (210 of 231) of patients. The linear support vector classification model has the best prediction results in training and test cohorts and the variables of age, A2 lesions, leaflet height, MR grades, and so on were risk factors for failure of mitral valve repair. ConclusionThe linear support vector classification prediction model may allow the evaluation of the complexity of mitral valve repair. Age, A2 lesions, leaflet height, MR grades, and so on may be associated with mitral repair failure.

Optimal Bivariate Order-Replacement Policies for a Multi-State Repairable System with Reliability Constraint

A bivariate order-replacement policy for a multi-state repairable system with imperfect repair is put forward in this paper, where the decisions on when to order a spare part and when to place a replacement are based on the number of failures. The geometric processes are generalized to depict the characteristics that the successive working times are shorter and shorter while the consecutive repair times are longer and longer. According to the renewal reward theorem, a constrained optimization model for the order-replacement policy is formulated, in which the aim is to minimize the expected long-run cost rate (ELRCR) under the constraint that system availability is not less than a predetermined availability requirement. General representations of the ELRCR and system availability are derived and an approximation result of the optimization model is given under certain assumptions. Illustrative examples are provided to validate the applicability of the proposed order-replacement model and show the advantage of the order-replacement policy for the multi-state repairable system.

Prostate cancer and liquid biopsies: Clinical applications and challenges.

Liquid biopsy has emerged as a valuable and minimally invasive tool for real-time detection of clinically actionable abnormalities across various cancer types. Its applicability is particularly compelling in the realm of prostate cancer, where novel therapeutic agents, including those targeting DNA repair systems, are under development. Despite these advancements, challenges persist in effectively screening for prostate cancer, enhancing risk stratification, and determining optimal approaches for treating advanced disease. Consequently, there is a pressing need for improved biomarkers to aid clinicians in decision-making within these contexts. Cell-free DNA and extracellular vesicle analysis have demonstrated promise in diagnosis, prognostication, assessment of treatment responses, and identification of emerging mechanisms of resistance. Nevertheless, obstacles must be addressed before liquid biopsies can be integrated into routine clinical practice. These challenges encompass preanalytical considerations such as sample collection and storage, methods of extracellular vesicle isolation and enrichment, and the need for enhanced interpretation of generated sequencing data. This review provides a comprehensive overview of current clinical opportunities in managing prostate cancer through blood-based liquid biopsy, highlighting the progress made, and acknowledging the challenges that remain. Additionally, we discuss the next steps required for the effective implementation of liquid biopsies in guiding personalized treatment strategies for prostate cancer.

Bacillus subtilis stress-associated mutagenesis and developmental DNA repair.

SUMMARYThe metabolic conditions that prevail during bacterial growth have evolved with the faithful operation of repair systems that recognize and eliminate DNA lesions caused by intracellular and exogenous agents. This idea is supported by the low rate of spontaneous mutations (10-9) that occur in replicating cells, maintaining genome integrity. In contrast, when growth and/or replication cease, bacteria frequently process DNA lesions in an error-prone manner. DNA repairs provide cells with the tools needed for maintaining homeostasis during stressful conditions and depend on the developmental context in which repair events occur. Thus, different physiological scenarios can be anticipated. In nutritionally stressed bacteria, different components of the base excision repair pathway may process damaged DNA in an error-prone approach, promoting genetic variability. Interestingly, suppressing the mismatch repair machinery and activating specific DNA glycosylases promote stationary-phase mutations. Current evidence also suggests that in resting cells, coupling repair processes to actively transcribed genes may promote multiple genetic transactions that are advantageous for stressed cells. DNA repair during sporulation is of interest as a model to understand how transcriptional processes influence the formation of mutations in conditions where replication is halted. Current reports indicate that transcriptional coupling repair-dependent and -independent processes operate in differentiating cells to process spontaneous and induced DNA damage and that error-prone synthesis of DNA is involved in these events. These and other noncanonical ways of DNA repair that contribute to mutagenesis, survival, and evolution are reviewed in this manuscript.

IMPROVING THE QUALITY OF MAINTENANCE AND REPAIR OF TRACTION SUBSTATIONS EQUIPMENT

The article deals with maintenance and repair of traction substations. The general problem of improving the maintenance and repair system of traction substations of electrified railways is described. An analysis of methods and means of maintenance and repair of substation equipment was carried out. The causes of malfunctions of the traction substations equipment are analyzed/ The distribution of malfunctions of TP equipment by types of equipment was analyzed. The results of transformer inspections are presented.

Process approach to managing a site &#x0D; Railroad repair system

Aim. This study aims to develop a scientific and practical tool for assessing the influence of the effectiveness of the district system of modernizing and current maintenance of railway tracks.&#x0D; Methods. To evaluate the process of introducing modern breakthrough technologies in terms of determining the time costs of work and the degree of their modification, the mathematical modeling method of business processes is used.&#x0D; Results. A model of the organization of the mechanized process of capital overhaul of the track was developed, and the economic efficiency of using satellite navigation during capital overhaul of the track was calculated.&#x0D; Conclusion. The introduction of digital technologies to control the depth of the ballast prism cutout during the operation of gravel-cleaning machines relative to the adjacent track successfully replaces the labor process of measuring with a horizontal rail with a leveling under the inner thread of the repaired track, excludes technological stops of machines, and reduces the time of work of machines and personnel and operational costs.

Overcoming radioresistance of breast cancer cells with MAP4K4 inhibitors

Mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) has recently emerged as a promising therapeutic target in cancer. In this study, we explored the biological function of MAP4K4 in radioresistant breast cancer cells using two MAP4K4 inhibitors, namely PF06260933 and GNE-495. Radioresistant SR and MR cells were established by exposing SK-BR-3 and MCF-7 breast cancer cells to 48–70 Gy of radiation delivered at 4–5 Gy twice a week over 10 months. Surprisingly, although radioresistant cells were derived from two different subtypes of breast cancer cell lines, MAP4K4 was significantly elevated regardless of subtype. Inhibition of MAP4K4 with PF06260933 or GNE-495 selectively targeted radioresistant cells and improved the response to irradiation. Furthermore, MAP4K4 inhibitors induced apoptosis through the accumulation of DNA damage by inhibiting DNA repair systems in radioresistant cells. Notably, Inhibition of MAP4K4 suppressed the expressions of ACSL4, suggesting that MAP4K4 functioned as an upstream effector of ACSL4. This study is the first to report that MAP4K4 plays a crucial role in mediating the radioresistance of breast cancer by acting upstream of ACSL4 to enhance DNA damage response and inhibit apoptosis. We hope that our findings provide a basis for the development of new drugs targeting MAP4K4 to overcome radioresistance.

An injectable polyacrylamide/chitosan-based hydrogel with highly adhesive, stretchable and electroconductive properties loaded with irbesartan for treatment of myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) significantly contributes to the high incidence of complications and mortality associated with acute myocardial infarction. Recently, injectable electroconductive hydrogels (IECHs) have emerged as promising tools for replicating the mechanical, electroconductive, and physiological characteristics of cardiac tissue. Herein, we aimed to develop a novel IECH by incorporating irbesartan as a drug delivery system (DDS) for cardiac repair. Our approach involved merging a conductive poly-thiophene derivative (PEDOT: PSS) with an injectable dual-network adhesive hydrogel (DNAH) comprising a catechol-branched polyacrylamide network and a chitosan-hyaluronic acid covalent network. The resulting P-DNAH hydrogel, benefitting from a high conducting polymer content, a chemically crosslinked network, a robust dissipative matrix, and dynamic oxidation of catechol to quinone exhibited superior mechanical strength, desirable conductivity, and robust wet-adhesiveness. In vitro experiments with the P-DNAH hydrogel carrying irbesartan (P-DNAH-I) demonstrated excellent biocompatibility by cck-8 kit on H9C2 cells and a rapid initial release of irbesartan. Upon injection into the infarcted hearts of MIRI mouse models, the P-DNAH-I hydrogel effectively inhibited the inflammatory response and reduced the infarct size. In conclusion, our results suggest that the P-DNAH hydrogel, possessing suitable mechanical properties and electroconductivity, serves as an ideal IECH for DDS, delivering irbesartan to promote heart repair.

Application of Reliability Centred Maintenance in Improving Aircraft Availability with Preventive Maintenance Intervention

Aircraft are intricate flying machines equipped with advanced technologies and state-of-the-art information and communication systems. Maintaining these aircraft to ensure maximum availability and minimal downtime is a critical and challenging task. Therefore, aircraft maintenance, repair, and servicing are of utmost importance. This research work aims to develop a methodology for reliability centred maintenance (RCM) to enhance aircraft availability. An RCM approach with the Multi attribute decision making (MADM) technique for assigning criticality of systems was implemented to improve aircraft availability. Failure mode and effects analysis (FMECA) was utilized for the failure investigation in the aircraft systems. However, instead of the Risk priority number (RPN) due to its inherent flaws, the Analytical hierarchy process (AHP) was utilized to evaluate the criticality of systems. The remedial measures to minimize the failure frequency and downtime were proposed. The improvement in availability, post implementation of proposed preventive maintenance was validated with positive results. An improvement of approximately 6.62% in availability and a reduction of about 15.71% in the total downtime was observed on the implementation of proposed preventive measures. The availability analysis was carried out for aircraft systems; however, the model could also be used for other repairable systems following a similar maintenance philosophy.