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Abstract Chemoresistance remains a significant challenge for effective breast cancer treatment which leads to cancer recurrence. CRISPR-directed gene editing becomes a powerful tool to reduce chemoresistance by reprogramming the tumor microenvironment. Previous research has revealed that Chinese herbal extracts have significant potential to overcome tumor chemoresistance. However, the therapeutic efficacy is often limited due to their poor tumor targeting and in vivo durability. Here we have developed a tumor microenvironment responsive nanoplatform (H-MnO2(ISL + DOX)-PTPN2@HA, M(I + D)PH) for nano-herb and CRISPR codelivery to reduce chemoresistance. Synergistic tumor inhibitory effects were achieved by the treatment of isoliquiritigenin (ISL) with doxorubicin (DOX), which were enhanced by CRISPR-based gene editing to target protein tyrosine phosphatase non-receptor type 2 (PTPN2) to initiate long-term immunotherapy. Efficient PTPN2 depletion was observed after treatment with M(I + D)PH nanoparticles, which resulted in the recruitment of intratumoral infiltrating lymphocytes and an increase of proinflammatory cytokines in the tumor tissue. Overall, our nanoparticle platform provides a diverse technique for accomplishing synergistic chemotherapy and immunotherapy, which offers an effective treatment alternative for malignant neoplasms. Graphical Abstract

Targeting androgen receptor (AR) has shown great therapeutic potential in triple-negative breast cancer (TNBC), yet its efficacy remains unsatisfactory. Here, we aimed to identify promising targeted agents that synergize with enzalutamide, a second-generation AR inhibitor, in TNBC. By using a strategy for screening drug combinations based on the Sensitivity Index (SI), we found that MK-8776, a selective checkpoint kinase1 (CHK1) inhibitor, showed favorable synergism with enzalutamide in AR-positive TNBC. The combination of enzalutamide and MK-8776 was found to exert more significant anti-tumor effects in TNBC than the single application of enzalutamide or MK-8776, respectively. Furthermore, a nanoparticle-based on hyaluronic acid (HA)-modified hollow-manganese dioxide (HMnO2), named HMnE&M@H, was established to encapsulate and deliver enzalutamide and MK-8776. This HA-modified nanosystem managed targeted activation via pH/glutathione responsiveness. HMnE&M@H repressed tumor growth more obviously than the simple addition of enzalutamide and MK-8776 without a carrier. Collectively, our study elucidated the synergy of enzalutamide and MK-8776 in TNBC and developed a novel tumor-targeted nano drug delivery system HMnE&M@H, providing a potential therapeutic approach for the treatment of TNBC.

Abstract. Background:. Dual-energy computed tomography (DECT) is purported to accurately distinguish uric acid stones from non-uric acid stones. However, whether DECT can accurately discriminate ammonium urate stones from uric acid stones remains unknown. Therefore, we aimed to explore whether they can be accurately identified by DECT and to develop a radiomics model to assist in distinguishing them. Methods:. This research included two steps. For the first purpose to evaluate the accuracy of DECT in the diagnosis of uric acid stones, 178 urolithiasis patients who underwent preoperative DECT between September 2016 and December 2019 were enrolled. For model construction, 93, 40, and 109 eligible urolithiasis patients treated between February 2013 and October 2022 were assigned to the training, internal validation, and external validation sets, respectively. Radiomics features were extracted from non-contrast CT images, and the least absolute shrinkage and selection operator (LASSO) algorithm was used to develop a radiomics signature. Then, a radiomics model incorporating the radiomics signature and clinical predictors was constructed. The performance of the model (discrimination, calibration, and clinical usefulness) was evaluated. Results:. When patients with ammonium urate stones were included in the analysis, the accuracy of DECT in the diagnosis of uric acid stones was significantly decreased. Sixty-two percent of ammonium urate stones were mistakenly diagnosed as uric acid stones by DECT. A radiomics model incorporating the radiomics signature, urine pH value, and urine white blood cell count was constructed. The model achieved good calibration and discrimination {area under the receiver operating characteristic curve (AUC; 95% confidence interval [CI]), 0.944 (0.899–0.989)}, which was internally and externally validated with AUCs of 0.895 (95% CI, 0.796–0.995) and 0.870 (95% CI, 0.769–0.972), respectively. Decision curve analysis revealed the clinical usefulness of the model. Conclusions:. DECT cannot accurately differentiate ammonium urate stones from uric acid stones. Our proposed radiomics model can serve as a complementary diagnostic tool for distinguishing them in vivo.

Despite advances in targeted therapies, primary and acquired resistance make the treatment of colorectal cancer (CRC) a pressing issue to be resolved. According to reports, the development of CRC is linked to miRNA dysregulation. Multiple studies have demonstrated that miR-135b-5p has an aberrant expression level between CRC tissues and adjacent tissues. However, it is unclear whether there is a correlation between miR-135b-5p and cetuximab (CTx) resistance in CRC. Use the GEO database to measure miR-135b-5p expression in CRC. Additionally, RT-qPCR was applied to ascertain the production level of miR-135b-5p in three human CRC cells and NCM460 cells. The capacity of cells to migrate and invade was examined utilizing the wound-healing and transwell assays, while the CCK-8 assay served for evaluating cell viability, as well as colony formation assays for proliferation. The expected target protein of miR-135b-5p in CRC cell cetuximab resistance has been investigated using western blot. Suppression of miR-135b-5p could increase the CTx sensitivity of CTx-resistant CRC cells, as manifested by the attenuation of proliferation, migration, and invasion ability. Mechanistic studies revealed miR-135b-5p regulates the epithelial-to-mesenchymal transition (EMT) process and Wnt/β-catenin signaling pathway through downgulating FOXN3. In short, knockdowning miR-135b-5p could increase FOXN3 expression in CRC cells, promote the EMT process, and simultaneously activate the Wnt/β-catenin signaling pathway to elevate CTx resistance in CRC cells.

ABSTRACTThis study aims to conduct a bibliometric analysis, employing visualization tools to examine literature pertaining to tumor immune evasion related to anti-CTLA-4 and anti-PD-1/PD-L1 therapy from 1999 to 2022. A special emphasis is placed on the interplay between tumor microenvironment, signaling pathways, immune cells and immune evasion, with data sourced from the Web of Science core collection (WoSCC). Advanced tools, including VOSviewer, Citespace, and Scimago Graphica, were utilized to analyze various parameters, such as co-authorship/co-citation patterns, regional contributions, journal preferences, keyword co-occurrences, and significant citation bursts. Out of 4778 publications reviewed, there was a marked increase in research focusing on immune evasion, with bladder cancer being notably prominent. Geographically, China, the USA, and Japan were the leading contributors. Prestigious institutions like MD Anderson Cancer Center, Harvard Medical School, Fudan University, and Sun Yat Sen University emerged as major players. Renowned journals in this domain included Frontiers in Immunology, Cancers, and Frontiers in Oncology. Ehen LP and Wang W were identified as prolific authors on this topic, while Topalian SL stood out as one of the most cited. Research current situation is notably pivoting toward challenges like immunotherapy resistance and the intricate signaling pathways driving drug resistance. This bibliometric study seeks to provide a comprehensive overview of past and current research trends, emphasizing the potential role of tumor microenvironment, signaling pathways and immune cells in the context of immune checkpoint inhibitors (ICIs) and tumor immune evasion.

Aims: To provide a comprehensive bibliometric overview of drug resistance in bladder cancer (BC) from 1999 to 2022, aiming to illuminate its historical progression and guide future investigative avenues. Methods: Literature on BC drug resistance between 1999 and 2022 was sourced from the Web of Science. Visual analyses were executed using Vosviewer and Citespace software, focusing on contributions by countries, institutions, journals, authors, references, and keywords. Results: From 2727 publications, a marked growth in BC drug resistance studies was discerned over the two decades. Prominent among all institutions is the University of Texas System. The majority of top-ranked journals were American. In authorship significance, McConkey DJ led in publications, while Bellmunt J dominated in citations. Research topics predominantly spanned cancer demographics, drug efficacy evaluations, molecular features, oncology subtypes, and individualized treatment strategies, with a notable contemporary emphasis on molecular mechanisms behind drug resistance and nuances of ICIs. Conclusions: Our bibliometric analysis charts the landscape of BC drug resistance research from 1999 to 2022. While the study of resistance mechanisms has been robust, there's an evident need for deeper exploration into the molecular intricacies and the potential of ICIs and targeted therapeutic strategies.

Background: The prognostic significance of tumor size with adrenocortical carcinoma (ACC) patients has not yet been thoroughly evaluated. Our objective was to investigate the influence of tumor size on prognostic value in adult ACC patients. Methods: The Surveillance, Epidemiology and End Results Program (SEER) was employed to identify adult ACC patients who had been diagnosed from 2004 to 2015. The “X-Tile” program determined the optimal cutoff value of tumor size. Cancer-specific survival (CSS) and overall survive (OS) were estimated. The survival outcomes and risk factors were analyzed by the Kaplan-Meier methods and the multivariable cox regression respectively. Results: A total 426 adult ACC patients were included. Univariable and multivariable cox analysis revealed age, larger tumor size and metastasis as consistent predictors of lower CSS and OS. The optimal cutoff value of tumor size was identified as 8.5 cm using X-tile software, and Kaplan-Meier method showed dramatic prognostic difference between patients with larger tumors (＞8.5 cm) and smaller tumors (≤8.5 cm) (log-rank test, P

Abstract Background Non-muscle invasive bladder cancer (NMIBC) is known for its elevated recurrence rate, necessitating an enhancement in the current risk stratification for recurrence. The urine-based fluorescence in situ hybridization (FISH) assay has emerged as a noninvasive auxiliary tool for detecting bladder cancer. The aim of this study was to explore the potential relationship between the preoperative FISH assay and recurrence, and to develop a FISH-clinical nomogram for predicting the recurrence-free survival (RFS) in NMIBC patients. Methods In total, 332 eligible patients were enrolled from two hospitals. The SYSMH cohort was randomly assigned to the training set (n = 168) and the validation set I (n = 72) at a ratio of 7:3, while the SYSUTH cohort was allocated to the validation set II (n = 92). The correlation between the preoperative FISH assay and recurrence was determined through the Cox regression analysis. The least absolute shrinkage and selection operator (LASSO) Cox regression algorithm was used for model construction. The performance of the model was assessed by its discrimination, calibration, and clinical usefulness. Results We uncovered that chromosome 7 aneuploidy, p16 locus loss, number of the positive FISH sites, and the FISH test result were significantly associated with tumor recurrence. Then, a FISH-clinical nomogram incorporating the FISH test result, T stage, associated CIS, tumor grade, and tumor status was developed. It showed favorable calibration and discrimination with a C-index of 0.683 (95%CI, 0.611–0.756) in the training set, which was confirmed in the validation set I and validation set II with C-indexes of 0.665 (95%CI, 0.565–0.765) and 0.778 (95%CI, 0.665–0.891), respectively. Decision curve analysis revealed the clinical usefulness of the nomogram. Moreover, our proposed nomogram significantly outperformed the guideline-recommended EORTC and CUETO scoring models. Conclusion Our study confirmed the prognostic value of the preoperative FISH assay and proposed a FISH-clinical nomogram to predict RFS in NMIBC patients. Our nomogram can serve as a more precise tool for recurrence risk stratification, which may optimize disease management in bladder cancer and improve patient prognosis.

BackgroundNeoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC) remains the cornerstone of treatment for muscle-invasive bladder cancer (MIBC). While platinum-based regimens have demonstrated benefits in tumor downstaging and improved long-term survival for selected patients, they may pose risks for those who are ineligible or unresponsive to chemotherapy.ObjectiveWe undertook a bibliometric analysis to elucidate the breadth of literature on NAC in bladder cancer, discern research trajectories, and underscore emerging avenues of investigation.MethodsA systematic search of the Web of Science Core Collection (WoSCC) was conducted to identify articles pertaining to NAC in bladder cancer from 1999 to 2022. Advanced bibliometric tools, such as VOSviewer, CiteSpace, and SCImago Graphica, facilitated the examination and depicted the publication trends, geographic contributions, institutional affiliations, journal prominence, author collaborations, and salient keywords, emphasizing the top 25 citation bursts.ResultsOur analysis included 1836 publications spanning 1999 to 2022, indicating a growing trend in both annual publications and citations related to NAC in bladder cancer. The United States emerged as the predominant contributor in terms of publications, citations, and international collaborations. The University of Texas was the leading institution in publication output. “Urologic Oncology Seminars and Original Investigations” was the primary publishing journal, while “European Urology” boasted the highest impact factor. Shariat, Shahrokh F., and Grossman, H.B., were identified as the most prolific and co-cited authors, respectively. Keyword analysis revealed both frequency of occurrence and citation bursts, highlighting areas of concentrated study. Notably, the integration of immunochemotherapy is projected to experience substantial growth in forthcoming research.ConclusionsOur bibliometric assessment provides a panoramic view of the research milieu surrounding neoadjuvant chemotherapy for bladder cancer, encapsulating the present state, evolving trends, and potential future directions, with a particular emphasis on the promise of immunochemotherapy.

Strong demand for electric vehicles and energy storage applications has led to a rapid expansion of the battery sector. Laser welding is widely used in lithium-ion batteries and manufacturing companies due to its high energy density and capability to join different materials. Welding quality plays a vital role in the durability and effectiveness of welding structures. Therefore, it is essential to monitor welding defects to ensure welds quality. Manual inspection, analysis and evaluation of welding defect images is difficult due to the non-uniformity in their shape, position, and size. Hence the use of deep learning techniques to identify welding defects is more accurate and reliable due to the adequate training data samples, which helps to identify welding defects with greater accuracy. In this study, we present a novel collection of 3,736 laser welding images which are labeled with eight classes. This dataset contains both normal and defective classes collected from a Dade Laser Chinese production line. Moreover, we introduce a modified loss function that integrates cross entropy and complement objective training. The EfficientNetB6 model is trained with the newly introduced loss function that performed efficiently and achieved a promising accuracy during the classification phase. The experimental results demonstrate the significance of the proposed loss function and the sufficiency of EfficientNetB6 model on the laser welding dataset. Compared to other models, EfficientNetB6 performs better.

The NLRP3 inflammasome plays a pivotal role in clearing viral respiratory infection, but the molecular mechanism is not fully known. Here authors show that acetate, produced by gut bacteria, may enhance NLRP3-mediated type I interferon production following influenza infection in mice.

Abstract Background Accurate pathological diagnosis of invasion depth and histologic grade is key for clinical management in patients with bladder cancer (BCa), but it is labour-intensive, experience-dependent and subject to interobserver variability. Here, we aimed to develop a pathological artificial intelligence diagnostic model (PAIDM) for BCa diagnosis. Methods A total of 854 whole slide images (WSIs) from 692 patients were included and divided into training and validation sets. The PAIDM was developed using the training set based on the deep learning algorithm ScanNet, and the performance was verified at the patch level in validation set 1 and at the WSI level in validation set 2. An independent validation cohort (validation set 3) was employed to compare the PAIDM and pathologists. Model performance was evaluated using the area under the curve (AUC), accuracy, sensitivity, specificity, positive predictive value and negative predictive value. Results The AUCs of the PAIDM were 0.878 (95% CI 0.875–0.881) at the patch level in validation set 1 and 0.870 (95% CI 0.805–0.923) at the WSI level in validation set 2. In comparing the PAIDM and pathologists, the PAIDM achieved an AUC of 0.847 (95% CI 0.779–0.905), which was non-inferior to the average diagnostic level of pathologists. There was high consistency between the model-predicted and manually annotated areas, improving the PAIDM’s interpretability. Conclusions We reported an artificial intelligence-based diagnostic model for BCa that performed well in identifying invasion depth and histologic grade. Importantly, the PAIDM performed admirably in patch-level recognition, with a promising application for transurethral resection specimens.

PurposeImmune checkpoint blockade agents were shown to provide a survival advantage in urothelial carcinoma, while some patients got minimal benefit or side effects. Therefore, we aimed to investigate the prognostic value of m6A methylation regulators, and developed a nomogram for predicting the response to atezolizumab in urothelial carcinoma patients.MethodsA total of 298 advanced urothelial carcinoma patients with response data in the IMvigor210 cohort were included. Differential expressions of 23 m6A methylation regulators in different treatment outcomes were conducted. Subsequently, a gene signature was developed in the training set using the least absolute shrinkage and selection operator (LASSO) regression. Based on the multivariable logistic regression, a nomogram was constructed by incorporating the gene signature and independent clinicopathological predictors. The performance of the nomogram was assessed by its discrimination, calibration, and clinical utility with internal validation.ResultsSix m6A methylation regulators, including IGF2BP1, IGF2BP3, YTHDF2, HNRNPA2B1, FMR1, and FTO, were significantly differentially expressed between the responders and non-responders. These six regulators were also significantly correlated with the treatment outcomes. Based on the LASSO regression analysis, the gene signature consisting of two selected m6A methylation regulators (FMR1 and HNRNPA2B1) was constructed and showed favorable discrimination. The nomogram integrating the gene signature, TMB, and PD-L1 expression on immune cells, showed favorable calibration and discrimination in the training set (AUC 0.768), which was confirmed in the validation set (AUC 0.755). Decision curve analysis confirmed the potential clinical usefulness of the nomogram.ConclusionsThis study confirmed the prognostic value of FMR1 and HNRNPA2B1, and constructed a nomogram for individualized prediction of the response to atezolizumab in patients with urothelial carcinoma, which may aid in making treatment strategies.

It is increasingly important to develop gas injection drive technology to improve the economic benefits of high water cut and low permeability reservoirs. By using the indoor physical simulation of the long core displacement experiment with two parallel pipes, this paper analyzes the interlayer difference of the target block in the high water cut reservoir. The experiments investigated the effect of various injection media, injection methods, and injection parameters on oil recovery and its internal mechanism. The best oil displacement system was then selected. The results demonstrated that nitrogen foam flooding can effectively plug the high permeability layer after nitrogen flooding. The foam enters the high permeability layer along the dominant seepage channel, completing the plugging of the high permeability core, increasing the swept volume of nitrogen in the low permeability core, and improving the low permeability core's recovery degree. The gas water alternative drive is suitable for water injection breakthrough and gas water alternative drive. The breakthrough time was late, and the contact time between gas and oil was extended, which is conducive to reducing the density and viscosity of crude oil. According to the research results of long core slug size, 0.05 HCPV slug size is suitable for gas water alternative flooding, which can maintain foam stability. The gas breakthrough time was late, and the plugging effect was pronounced. The displacement effect of hydrocarbon gas was superior to that of deoxidized air, and the total water content of the hydrocarbon gas drive was less than that of the deoxidized air drive. The gas breakthrough time for hydrocarbon gas water alternative drives was 0.1 PV later than for deoxidized air water alternative drives. Gas swept volume was more significant, so it is considered the preferred injection medium. [ABSTRACT FROM AUTHOR]

The advantages of using electrodynamic treatment (EDT) of metal in the welding process as compared to EDT at room temperature were substantiated. The advantages and disadvantages of using electrode for EDT in the form of a cylindrical rod and a roller in the welding process were considered. Using the method of mathematical modeling in planar and axisymmetric statements, the effect of the shape of the electrode-indenter on stress-strain state of the welded plate from aluminum AMg6 alloy after applying the dynamic EDT component was evaluated. The features and differences of creation and use of developed mathematical models were described. The distribution of the values of the stress-strain state throughout the thickness of the plate was determined, in particular, the values of the zone of plastic deformations and stresses during interaction of the plate with the electrode-indenter moving at a speed of 5 m/s. It was found that the use of a cylindrical indenter with a hemispherical working end (axisymmetric shape) as compared to the roller (plane elongated shape) is more effective from the standpoint of optimizing the residual stress state in the plate. The use of a cylindrical indenter leads to the formation of compressive stresses in the plate with the values of up to -120 MPa. This should have a positive effect on the distribution of residual welding stresses under the action of the dynamic EDT component. 4 Ref., 3 Tabl., 7 Fig. [ABSTRACT FROM AUTHOR]

The advantages of using electrodynamic treatment (eDt) of metal in the welding process as compared to eDt at room temperature were substantiated. the advantages and disadvantages of using electrode for eDt in the form of a cylindrical rod and a roller in the welding process were considered. using the method of mathematical modeling in planar and axisymmetric statements, the effect of a shape of the electrode-indenter on stress-strain state of the welded plate from aluminium aMg6 alloy after applying the dynamic eDt component was evaluated. the features and differences of creation and use of developed mathematical models were described. the distribution of values of the stress-strain state throughout the thickness of the plate was determined, in particular, the values of the zone of plastic deformations and stresses during interaction of the plate with the electrode-indenter moving at a speed of 5 m/s. It was found that the use of a cylindrical indenter with a hemispherical working end (of axisymmetric shape) as compared to the roller (of planar elongated shape) is more effective from the standpoint of optimizing the residual stressed state in the plate. the use of a cylindrical indenter leads to the formation of compressive stresses in the plate with the values up to -120 MPa. This should have a positive effect on the distribution of residual welding stresses under the action of the dynamic eDt component. [ABSTRACT FROM AUTHOR]

Light metal alloys (in particular, beryllium and aluminium) are applied in different engineering fields, for instance for fabrication of rocket and aircraft elements. When designing such engineering elements, there is the need to produce welded joints with different types of welds. Laser welding with nonthrough thickness penetration can be used for item sealing, welding-on flanges and welding thin-walled structures of up to 2-3 mm thickness. Toxic fumes form in welding beryllium alloys. Such a peculiarity requires reducing the number of technological experiments, aimed at selection of mode parameters. An up-to-date approach to solving the problem of light alloy welding is performance of preliminary calculated determination of mode parameters with their further experimental verification. Technological verification can be performed on high-strength aluminium alloys close by their physico-mechanical characteristics to beryllium alloys. Therefore, this work is devoted to preliminary determination of mode parameters of laser welding by a sealing weld with nonthrough thickness penetration of thin-walled flanges of cylindrical parts and box-shaped items from light metals and alloys based on Be and Al, taking into account the temperature of heating after welding. A procedure of preliminary calculated determination of mode parameters of laser welding of parts from a berylliumbased alloy is proposed in the work, which is suitable for both through-thickness and nonthrough-thickness penetration. Nonthrough-thickness penetration can be applied for welding-on flanges by a sealing weld. Experimental verification on samples from alloys of Al–Zn–Mg–Cu system and comparison with published data on beryllium alloy welding showed that the error of the proposed procedure is in the range of up to 15 – 20%. [ABSTRACT FROM AUTHOR]

Light metal alloys (in particular, beryllium and aluminium) are applied in different engineering fields, for instance for fabrication of rocket and aircraft elements. When designing such engineering elements, there is the need to produce welded joints with different types of welds. Laser welding with nonthrough thickness penetration welds can be used for item sealing, welding-on flanges and welding thin-walled structures of up to 2-3 mm thickness. Toxic fumes form in welding beryllium alloys. Such a peculiarity requires reducing the number of technological experiments, aimed at selection of mode parameters. An up-to-date approach to solving the problem of light alloy welding is performance of preliminary calculated determination of mode parameters with their further experimental verification. Technological verification can be performed on high-strength aluminium alloys close by their physico-mechanical characteristics to beryllium alloys. Therefore, this work is devoted to preliminary determination of mode parameters of laser welding by a sealing weld with nonthrough thickness penetration of thin-walled flanges of cylindrical parts and box-shaped items from light metals and alloys based on Be and Al, taking into account the temperature of postweld heating. A procedure of preliminary calculated determination of mode parameters of laser welding of parts from a beryllium-based alloy is proposed in the work, which is suitable for both through-thickness and nonthrough-thickness penetration. Nonthrough-thickness penetration can be applied for welding-on flanges by a sealing weld. Experimental verification on samples from alloys of Al-Zn-Mg-Cu system and comparison with published data on beryllium alloy welding showed that the error of the proposed procedure is in the range of up to 15-20 %. [ABSTRACT FROM AUTHOR]

The paper deals with the features of laser welding with incomplete (non-through thickness) penetration of high-strength aluminium alloys of 7ххх series. It was found that at joining of 1.5 mm sheets by fibre laser welding to the depth of 0.5…0.7 mm there arises the risk of formation of pores, in particular, in the root zone, streaks of oxide film in the weld lower part, as well as hot cracks. The latter can be eliminated by reducing the heat input below 25 – 30 J/mm. The weld metal is characterized by an equiaxed finely dispersed structure with grain size of 10…15 ~m for 7005 alloy and 15…25 ~m for 7075 alloy. In the fusion zone, the grains are of an elongated shape with 2.5…3.0 coefficient for 7005 alloy and 2…5 for 7075 alloy. In the HAZ the grain length is reduced, the shape coefficient becomes 3…5 and 3.0…3.5 for 7005 and 7075 alloys, respectively. At performance of laser welding with small (~5 J/mm) values of the heat input, microhardness of the welds and HAZ is rather uniform, and close to that of the base metal. For 7075 alloy microhardness drop to 20% was observed in the fusion zone region, that is due to formation of grains of an elongated shape with shape coefficient of 2…5. The found drawbacks can be eliminated through reduction of pulsations of the vapour-gas channel with simultaneous increase of the stability of its existence and introduction of cathode breaking of the oxide film. [ABSTRACT FROM AUTHOR]

This paper reports a study into features of the formation of structures of permanent butt joints of plates with a thickness of 1.5 mm made from the high-strength aluminum alloy 7075 of the Al-Zn-Mg-Cu system. Welding by melting these joints was performed using three techniques: laser, microplasma, and hybrid laser-microplasma. To implement the latter two, a compressed arc on a multipolar asymmetric current was used. The purpose of the research was to establish the tendency to the formation of characteristic defects and the possibility of their elimination. It has been determined that during laser welding a small (~5 %) volumetric fraction of defects in the form of pores is formed, residual welding deformations are minimized. There is a decrease in the hardness of the melted metal by 15 % with a simultaneous increase in the hardness of the heat-affected zone (HAZ) by 8...12 % relative to the base metal. In the melted metal, cavities up to 100 μm in size are formed, which are the center of the origin of hot cracks with a length of 25‒30 μm. There are oxide inclusions in the root part of the seam. With microplasma welding, the volume fraction of defects of the melted metal in the form of pores with a size of 10...105 μm increases (up to 25 %). The hardness of the melted metal is reduced by 30 % with the hardness of the HAZ metal close to the base metal. In laser-microplasma welding, the volumetric fraction of defects of the melted metal in the form of pores with a size of 15...25 μm is reduced to 5 %. The hardness of the melted metal is reduced by 15...20 % with the hardness of the HAZ metal close to the base metal. In the lower part of the melted metal, cavities of ~100 μm are formed. No microcracks were found in the seam metal. Analysis of the research results showed the advantage of the laser-microplasma technique. This method reduces the use of laser energy by 40...50 %, the lifetime of the welding pool (0.03...0.05 s) approaches laser welding, it eliminates the danger of burnout of alloying elements. [ABSTRACT FROM AUTHOR]

The paper is devoted to studying the technological features of plasma-arc spraying by consumable current-conducting wire-anode. The relevance of applying such a process is related to the possibility of spraying directly by atomization of wires without the need to make powders from them. Experimental verification of the results of mathematical prediction of the influence of annular protective flow of compressed air, accompanying the particle-loaded plasma jet, on the results of plasma-arc spraying by compact wire anodes was performed. The key role of increasing this flow rate above 20 m³/h for improvement of the spay-deposited coating formation and quality was established. In spraying of coatings from compact wires porosity decreased with increase of the values of flow rates of accompanying air flow G2, and achievement of this parameter values within 0.5…2.5 %. Conducted experiments allow producing porefree coatings in spraying with wires from М2 copper, Kh20N80 nichrome, NP1 nickel, AMg63 aluminium-magnesium alloy. Studying these experimental results showed that at increase of the rate of accompanying protective air flow G2 from 0 to 40 m³/h, the loss of alloying elements (С, Mn) during spraying by steels wires of 65G and 70 grades decreases by 30…40 % on average. Increase of the parameter of rate G2 of the air flow accompanying the particle-loaded plasma jet influences improvement of the coating adhesion strength and wear resistance. So, at G2 = 20…40 m³/h the adhesion strength at tearing off of coatings from steel 70 along the normal reaches 60…70 MPa, and that of coatings from М2 copper is 40…55 MPa. Wear resistance of coatings under the conditions of boundary friction and resistance at cavitation wear increases at G2 increase from 0 to 40 m3/h, which is manifested in reduction of such wear from 1.35 to 0.32 mg/min. 13 Ref., 9 Fig. [ABSTRACT FROM AUTHOR]