Search

As a metal additive manufacturing process, laser cladding (LC) is employed as a novel and beneficial repair technology for damaged steel structures. This study employed LC technology with 316 L stainless steel powder to repair locally corroded steel plates. The influences of interface slope and scanning pattern on the mechanical properties of repaired specimens were investigated through tensile tests and finite element analysis. By comparing the tensile properties of the repaired specimens with those of the intact and corroded specimens, the effectiveness of LC repair technology was assessed. An analysis of strain variations in the LC sheet and substrate during the load was carried out to obtain the cooperation mechanism between the LC sheet and substrate. The experimental results showed that the decrease in interface slope slightly improved the mechanical properties of repaired specimens. The repaired specimens have similar yield strength and ultimate strength to the intact specimens and better ductility as compared to the corroded specimen. The stress–strain curve of repaired specimens can be divided into four stages: elastic stage, substrate yield-LC sheet elastic stage, substrate hardening-LC sheet elastic stage, and plastic stage. These findings suggest that the LC technology with 316 L stainless steel powder is effective in repairing damaged steel plates in civil engineering structures and that an interface slope of 1:2.5 with the transverse scanning pattern is suitable for the repair process. [ABSTRACT FROM AUTHOR]

Radiotherapy (RT), including external beam radiation therapy (EBRT) and radionuclide therapy (RNT), realizes physical killing of local tumors and activates systemic anti-tumor immunity. However, these effects need to be further strengthened and the difference between EBRT and RNT should be discovered. Herein, bacterial outer membrane (OM) was biomineralized with manganese oxide (MnO2) to obtain OM@MnO2-PEG nanoparticles for enhanced radio-immunotherapy via amplifying EBRT/RNT-induced immunogenic cell death (ICD) and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) activation. OM@MnO2-PEG can react with H2O2 and then gradually produce O2, Mn2+ and OM fragments in the tumor microenvironment. The relieved tumor hypoxia improves the radio-sensitivity of tumor cells, resulting in enhanced ICD and DNA damage. Mn2+ together with the DNA fragments in the cytoplasm activate the cGAS-STING pathway, further exhibiting a positive role in various aspects of innate immunity and adaptive immunity. Besides, OM fragments promote tumor antigen presentation and anti-tumor macrophages polarization. More importantly, our study reveals that OM@MnO2-PEG-mediated RNT triggers much stronger cGAS-STING pathway-involved immunotherapy than that of EBRT, owing to the duration difference of RT. Therefore, this study develops a powerful sensitizer of radio-immunotherapy and uncovers some differences between EBRT and RNT in the activation of cGAS-STING pathway-related anti-tumor immunity. [ABSTRACT FROM AUTHOR]

Objectives: To develop and validate an ultrasound (US) radiomics-based nomogram for the preoperative prediction of the lymphovascular invasion (LVI) status in patients with invasive breast cancer (IBC). Materials and methods: In this multicentre, retrospective study, 456 consecutive women were enrolled from three institutions. Institutions 1 and 2 were used to train (n = 320) and test (n = 136), and 130 patients from institution 3 were used for external validation. Radiomics features that reflected tumour information were derived from grey-scale US images. The least absolute shrinkage and selection operator and the maximum relevance minimum redundancy (mRMR) algorithm were used for feature selection and radiomics signature (RS) building. US radiomics-based nomogram was constructed by using multivariable logistic regression analysis. Predictive performance was assessed with the receiving operating characteristic curve, discrimination, and calibration. Results: The nomogram based on clinico-ultrasonic features (menopausal status, US-reported lymph node status, posterior echo features) and RS yielded an optimal AUC of 0.88 (95% confidence interval [CI], 0.84–0.91), 0.89 (95% CI, 0.84–0.94) and 0.95 (95% CI, 0.92–0.99) in the training, internal and external validation cohort. The nomogram outperformed the clinico-ultrasonic and RS model (p < 0.05). The nomogram performed favourable discrimination (C-index, 0.88; 95% CI: 0.84–0.91) and was confirmed in the validation (0.88 for internal, 0.95 for external) cohorts. The calibration and decision curve demonstrated the nomogram showed good calibration and was clinically useful. Conclusions: The radiomics nomogram incorporated in the RS and US and the clinical findings exhibited favourable preoperative individualised prediction of LVI. Clinical relevance statement: The US radiomics-based nomogram incorporating menopausal status, posterior echo features, US reported-ALN status, and radiomics signature has the potential to predict lymphovascular invasion in patients with invasive breast cancer. Key Points: • The clinico-ultrsonic model of menopausal status, posterior echo features, and US-reported ALN status achieved a better predictive efficacy for LVI than either of them alone. • The radiomics nomogram showed optimal prediction in predicting LVI from patients with IBC (ROC, 0.88 and 0.89 in the training and validation sets). • A nomogram demonstrated favourable performance (area under the receiver operating characteristic curve, 0.95) and well calibration (C-index, 0.95) in an independent validation cohort (n = 130). [ABSTRACT FROM AUTHOR]

Background and Aim: To determine the factors contributing to successful mitral valve repair (MVP) and to discuss the effect of complex techniques on the durability of MVP for active infective endocarditis (IE) affecting the mitral valve.Methods: One hundred and eighty-seven patients were enrolled; 39.6% underwent mitral valve replacement (MVR) and 60.4% underwent MVP. We used logistic regression to identify influencing factors of the choice of surgical technique. The results were compared between groups and subgroups after propensity score matching (PSM).Results: Risk factors for MVR included poor valve quality (odds ratio [OR] 23.3, p = .001), a large defect after debridement (OR 16.4, p < .001), and heavy valve infection (OR 3.7, p = .027). After PSM, we did not find a significant difference in the frequency of major postoperative complications or the in-hospital or postdischarge death rate. The reintervention rate for MVP was significantly higher than that for MVR (p = .047). Subgroup analysis found a significant relationship between the use of a complex repair technique and the need for reoperation (p = .020).Conclusions: The choice of valve repair or replacement for patients with active IE affecting the mitral valve was influenced by the intraoperative characteristics of the infected valve rather than the severity of systemic infection or overall health status. The choice of surgical treatment strategy had no effect on major postoperative complications, in-hospital mortality, or medium-term survival. However, the medium-term durability of MVP was poorer than that of MVR. The use of the patch technique for free margins or extensive leaflet defects was associated with a need for reintervention. [ABSTRACT FROM AUTHOR]

Tumor-targeting attenuated Salmonella could induce certain antitumor therapeutic effect through its proliferation characteristic and the consequent activated immune response, while host defense cells represented by neutrophils would trap and eliminate these invading bacteria via producing excess hydrogen peroxide (H2O2)-including reactive oxygen species in the bacteria-infected tumor, thereby impairing the efficacy of the bacteria treatment of tumor. Herein, we attempt to combine bacteria treatment and oxygen-dependent radioimmunotherapy of tumor through injection of neutrophil-targeted nano-catalase into the bacteria-treated mice for perfect tumor treatment outcome. Denatured albumin is used to coat catalase and deliver it to the neutrophils infiltrated in bacteria-infected tumor tissue. Taking advantage of the generating H2O2 by neutrophils, easily-diffused oxygen is produced and spread the whole tumor under the catalysis of nano-enzyme, leading to enhanced radiotherapy of hypoxic tumor cells. Moreover, the optimized tumor microenvironment, synergistically caused by potent immune-stimulation of bacteria, generating oxygen and tumor radiotherapy, would boost the antitumor immunity. This novel combination therapy strategy holds great promise to provide new ideas for future clinical cancer treatment. [ABSTRACT FROM AUTHOR]

Background: The coronavirus disease 2019 (COVID-19) pandemic has been and will continue to be a challenge to the healthcare system worldwide. In this context, we aimed to discuss the impact of the COVID-19 pandemic on the diagnosis, timing, and prognosis of surgical treatment for active infective endocarditis (IE) during the pandemic and share our coping strategy.Methods: A total of 39 patients were admitted for active IE in the year 2020. The number of the same period last year was 50. Medical information of these two groups was extracted from our surgical database. Data were compared between the two groups and differences with or without statistical significance were discussed.Results: In the pandemic year, we admitted fewer transferred patients (64.1% vs. 80%, p = .094). Timespan for diagnosis were prolonged (60 vs. 34.5 days, p = .081). More patients were admitted in emergency (41% vs. 20%, p = .030) More patients had heart failure (74.4% vs. 40%, p = .001), sepsis (69.2% vs. 42.0%, p = .018), or cardiogenic shock (25.6% vs. 8.0%, p = .038). Overall surgical risk (EuroSCORE II) was higher (4.15% vs. 3.24%, p = .019) and more commando surgery was performed (7.7% vs. 2.0%, p = .441). However, we did not see more postoperative complications, and early mortality was not worse either (0 vs. 4%, p = .502).Conclusions: The negative impact of the COVID-19 pandemic on the clinical practice of surgical treatment for active IE was multifaceted. However, with the preservation of the effectiveness of multidisciplinary IE surgical team, the early outcomes were comparable with those in the normal years. [ABSTRACT FROM AUTHOR]

A series of experimental tests for investigating the post-fire mechanical (PFM) and post-fire fracture (PFF) performances of high strength steel Q460 are reported in this paper. All Q460 coupon specimens are heated up to a designated temperature which is selected from 100 to 900°C and then cooled down naturally to room temperature. Tensile tests are conducted to obtain their completely full-range post-fire stress-strain curves and the corresponding mechanical properties. The obtained experimental results show that with an increase in the heating temperature, the post-fire yield strength and ultimate strength of the Q460 structural steel decrease particularly when the heating temperature is over 650°C, but the post-fire elongation enhances. Ductile fracture behaviour of the coupon specimens under axial tensile loading can also be observed through the tensile coupon tests. The obtained experimental data are compared with the other results found in the open literatures on Grade 460 high strength steel. Based on a wider range of experimental data sets, predictive equations for evaluating the PFM properties of Grade 460 high strength steel are proposed. The experimental results presented in this study will provide benchmark data for the future calibration of complex ductile fracture parameters applied in numerical simulation. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) triggered mostly by infection, is a syndrome that involves respiratory failure. ARDS induces strong local infiltration of regulatory T cells (Treg cells) in the lungs, and Treg cells were recently highlighted as being related to the repair of various tissue. However, at present, there is still a lack of adequate evidence showing the impact of Treg cells on pulmonary regeneration during ARDS. Here, we verified that Treg cells are strongly induced in ARDS mice and Treg depletion results in impaired lung repair. Moreover, Treg cells show high expression of ST2, a cellular receptor for the tissue alarmin IL-33, which is strongly upregulated in the lung during ARDS. In addition, we demonstrated that IL-33 signaling is crucial for Treg cell accumulation, and ST2-blocked mice show a decrease in the Treg cell population. Critically, transfer of exogenous IL-33 into Treg depleted mice restored Treg cells and facilitated lung regeneration by promoting alveolar type II cell (AEC2) recovery in ARDS, with elevated neutrophils infiltration and upregulated TGF-β1 release. These results emphasized the importance of IL-33 in accelerating the expansion of pulmonary Treg cells and promoting their activity to mediate pulmonary epithelial regeneration during ARDS in a TGF-β1-dependent manner. [ABSTRACT FROM AUTHOR]

Background: Brachytherapy is a targeted type of radiotherapy utilized in the treatment of cancers. Elastin-like polypeptides are a unique class of genetically engineered peptide polymers that have several attractive properties for brachytherapy.Aims: To explore the feasibility and application of brachytherapy for VX2 liver tumor using elastin-like polypeptides with (131)I so as to provide reliable experimental evidence for a new promising treatment of liver cancer.Methods: Elastin-like polypeptide as carrier was labeled with (131)I using the iodogen method. Ten eligible rabbits with VX2 liver tumor were randomly divided into the treatment group (n = 5) and control group (n = 5). The treatment group received brachytherapy using elastin-like polypeptide with (131)I, and in the control group, elastin-like polypeptide was injected into the VX2 liver tumor as a control. Periodic biochemical and imaging surveillances were required to assess treatment efficacy.Results: The stability of elastin-like polypeptide with (131)I in vitro was maintained at over 96.8 % for 96 h. Biochemistry and imaging indicated brachytherapy using elastin-like polypeptide with (131)I for liver tumor can improve liver function and inhibit tumor growth (P < 0.05).Conclusions: Elastin-like polypeptide can be an ideal carrier of (131)I and have high labeling efficiency, radiochemical purity and stability. Brachytherapy using elastin-like polypeptide with (131)I for liver tumor is a useful therapy that possesses high antitumor efficacy advantages. [ABSTRACT FROM AUTHOR]

The transverse free vibration of an axially moving beam made of functionally graded materials (FGM) is investigated using a Timoshenko beam theory. Natural frequencies, vibration modes, and critical speeds of such axially moving systems are determined and discussed in detail. The material properties are assumed to vary continuously through the thickness of the beam according to a power law distribution. Hamilton’s principle is employed to derive the governing equation and a complex mode approach is utilized to obtain the transverse dynamical behaviors including the vibration modes and natural frequencies. Effects of the axially moving speed and the power-law exponent on the dynamic responses are examined. Some numerical examples are presented to reveal the differences of natural frequencies for Timoshenko beam model and Euler beam model. Moreover, the critical speed is determined numerically to indicate its variation with respect to the power-law exponent, axial initial stress, and length to thickness ratio. [ABSTRACT FROM AUTHOR]

This paper develops a numerical formulation for the nonlinear time-dependent analysis of steel-concrete composite members that are curved arbitrarily in space, which includes the effects of concrete shrinkage, creep, and geometric nonlinearity. This formulation is applicable to the analysis of composite arches and composite beams curved in plan, representing the limiting cases of members that are vertically and horizontally curved. The flexibility of the shear connection at the interface surface between the steel girder and the concrete deck is taken into consideration in the formulation. For an accurate serviceability limit state analysis of composite curved members, it is essential to include the shrinkage and creep response of the concrete component in the analysis. To also include the effects of geometric nonlinearity, a step-by-step incremental iterative solution procedure is adopted. Comparisons of the numerical solutions with those based on much less efficient and tractable viscoelastic ABAQUS shell element models, and with available experimental results, verify the accuracy of the computational formulation that is developed. Examples are chosen to illustrate the effects of partial interaction and initial curvature on the time-dependent behavior of spatially curved composite beams. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive experimental study of the time-dependent creep and shrinkage behavior of a simply supported steel-concrete composite beam that is curved in its plan; it is a companion to the first paper that presented a numerical model for spatially curved members for which a beam curved in plan is a limiting case. The full-scale beam was tested under sustained uniformly distributed loading for approximately 250 days; its time-dependent deformations and strains were monitored throughout the period of loading. Separate companion concrete specimens were tested under the same ambient conditions as the test beam to determine the creep and shrinkage characteristics of the concrete component of the beam. The test observations show that the creep and shrinkage behavior of the concrete component has a significant effect on the long-term response of curved composite beams. The experiment also provides benchmark data to test the validity of theoretical models and shows that the developed numerical technique is able to predict the deflections of the test beam acurately; hence, it is able to provide a reliable computational model from which to formulate design guidance. [ABSTRACT FROM AUTHOR]