Facile route to bulk ultrafine-grain steels for high strength and ductility.

Steels with sub-micrometre grain sizes usually possess high toughness and strength, which makes them promising for lightweighting technologies and energy-saving strategies. So far, the industrial fabrication of ultrafine-grained (UFG) alloys, which generally relies on the manipulation of diffusional phase transformation, has been limited to steels with austenite-to-ferrite transformation1-3. Moreover, the limited work hardening and uniform elongation of these UFG steels1,4,5 hinder their widespread application. Here we report the facile mass production of UFG structures in a typical Fe-22Mn-0.6C twinning-induced plasticity steel by minor Cu alloying and manipulation of the recrystallization process through the intragranular nanoprecipitation (within 30 seconds) of a coherent disordered Cu-rich phase. The rapid and copious nanoprecipitation not only prevents the growth of the freshly recrystallized sub-micrometre grains but also enhances the thermal stability of the obtained UFG structure through the Zener pinning mechanism6. Moreover, owing to their full coherency and disordered nature, the precipitates exhibit weak interactions with dislocations under loading. This approach enables the preparation of a fully recrystallized UFG structure with a grain size of 800 ± 400 nanometres without the introduction of detrimental lattice defects such as brittle particles and segregated boundaries. Compared with the steel to which no Cu was added, the yield strength of the UFG structure was doubled to around 710 megapascals, with a uniform ductility of 45 per cent and a tensile strength of around 2,000 megapascals. This grain-refinement concept should be extendable to other alloy systems, and the manufacturing processes can be readily applied to existing industrial production lines.

Survival and tumor characteristics of patients presenting with single primary versus second primary melanoma lesions.

BACKGROUND: Patients with single primary melanomas have an increased risk of developing subsequent melanomas. Secondary tumors diagnosed within and after 3 months are termed "synchronous" and "asynchronous," respectively. OBJECTIVE: To compare tumor distributions and survival characteristics between patients with second primary melanomas and those with single primary melanomas. METHODS: Retrospective cohort study. Data were collected from an institutional database from 14,029 patients with a diagnosis of a primary melanoma seen between 1970 and 2004. RESULTS: The synchronous and asynchronous cohorts demonstrated significantly improved survival probabilities compared with the single primary cohort (P = .04 and .002, respectively). Single primary lesions (2.2 ± 2.3 mm) were significantly thicker than the first-identified synchronous (2.0 ± 1.7 mm) and asynchronous (1.7 ± 1.3 mm) lesions. Synchronous lesions were more likely to be anatomically concordant compared with asynchronous lesions (55.7% vs 38.2%, P < .001). LIMITATIONS: Single-center study design and incomplete records for second primary melanoma Breslow depth and histopathology. CONCLUSION: Patients with second primary melanomas demonstrated a significant survival advantage and thinner lesions compared with those with single primary melanomas. Our reported tumor distributions support the role of full body skin examinations, with attention to the region of initial diagnosis.

Antibiotic Prophylaxis for Megaprosthetic Reconstructions: Drug and Dosing May Matter More than Duration.

In orthopedic oncology, the implant of a megaprosthetic device is standard of care after large-scale tumor resection involving segmental removal of bone. Infection remains the leading cause of implant failure, often resulting in major morbidity. Perioperative antibiotic practices for megaprosthetic reconstructions are not standardized and are based on guidelines for conventional joint arthroplasties. This study aims to evaluate the efficacy of current prophylactic strategies for megaprosthetic reconstructions. We conducted a retrospective review of megaprosthetic reconstructions performed at Duke University from 2001 to 2021. Logistic regression with GEE was used to assess whether a prolonged course of postoperative antibiotics is associated with infection risk. We assessed the microbial profile and corresponding susceptibilities of megaprosthetic infections through record review. Additionally, we designed a pharmacokinetic subgroup analysis using liquid chromatography-tandem mass spectrometry to quantify antibiotic concentrations in surgical tissue. Wilcoxon rank-sum tests were used to correlate tissue concentrations with infection risk. Out of 184 cases, 23 (12.5%) developed infection within 1 year. Extended postoperative antibiotics were not significantly associated with infection risk (P = 0.23). Among 18 culture-positive cases, 4 (22.2%) were caused by cefazolin-susceptible organisms. Median bone and muscle concentrations of cefazolin among cases that developed postoperative infection (0.065 ng/mL and 0.2 ng/mL, respectively) were significantly lower than those of cases that did not (0.42 ng/mL and 1.95 ng/mL, P < 0.01 and P = 0.03). This study is the first to comprehensively assess aspects of perioperative prophylaxis for megaprosthetic reconstructions. Extending postoperative antibiotics did not reduce infection risk. We detected a high frequency of cefazolin nonsusceptible organisms among postoperative infections. Additionally, intraoperative antibiotic tissue concentrations may be predictive of later infection. Future studies ought to examine optimal drug choices and dosing strategies.

Investigating readmission rates for patients undergoing oncologic resection and endoprosthetic reconstruction for primary sarcomas and tumors involving bone.

BACKGROUND: Little is known about the drivers of readmission in patients undergoing Orthopaedic oncologic resection. The goal of this study was to identify factors independently associated with 90-day readmission for patients undergoing oncologic resection and subsequent prosthetic reconstruction for primary tumors involving bone. METHODS: This was a retrospective comparative cohort study of patients treated from 2008 to 2019 who underwent endoprosthetic reconstruction for a primary bone tumor or soft tissue tumor involving bone, as well as those who underwent a revision endoprosthetic reconstruction if the primary endoprosthetic reconstruction was performed for an oncologic resection. The primary outcome measure was unplanned 90-day readmission. RESULTS: A total of 149 patients were identified who underwent 191 surgeries were for a primary bone or soft tissue tumor. The 90-day readmission rate was 28.3%. Female gender, depression, higher tumor grade, vascular reconstruction, longer procedure duration, longer length of stay (LOS), multiple surgeries during an admission and disposition to a Skilled Nursing Facility were associated with readmission (p < 0.05). In a multivariate analysis, female sex, higher tumor grade and longer procedure duration were independently associated with risk of readmission (p < 0.05). CONCLUSIONS: Readmission rates are high following endoprosthetic reconstruction for Orthopaedic oncologic resections. Further work is necessary to help minimize unplanned readmissions.

Expanding Beyond Maximum Grade: Chemotherapy Toxicity over Time by Age and Performance Status in Advanced Non-Small Cell Lung Cancer in CALGB 9730 (Alliance A151729).

BACKGROUND: Prior comparisons of chemotherapy adverse events (AEs) by age and performance status (PS) are limited by the traditional maximum grade approach, which ignores low-grade AEs and longitudinal changes. MATERIALS AND METHODS: To compare fatigue and neuropathy longitudinally by age (<65, ≥65 years) and PS (0-1, 2), we analyzed data from a large phase III trial of carboplatin and paclitaxel versus paclitaxel for advanced non-small cell lung cancer (CALGB 9730, n = 529). We performed multivariable (a) linear mixed models to estimate mean AE grade over time, (b) linear regression to estimate area under the curve (AUC), and (c) proportional hazards models to estimate the hazard ratio of developing grade ≥2 AE, as well as traditional maximum grade analyses. RESULTS: Older patients had on average a 0.17-point (95% confidence interval [CI], 0.00-0.34; p = .049) higher mean fatigue grade longitudinally compared with younger patients. PS 2 was associated with earlier development of grade ≥2 fatigue (hazard ratio [HR], 1.56; 95% CI, 1.07-2.27; p = .02). For neuropathy, older age was associated with earlier development of grade ≥2 neuropathy (HR, 1.41; 95% CI, 1.00-1.97; p = .049). Patients with PS 2 had a 1.30 point lower neuropathy AUC (95% CI, -2.36 to -0.25; p = .02) compared with PS 0-1. In contrast, maximum grade analyses only detected a higher percentage of older adults with grade ≥3 fatigue and neuropathy at some point during treatment. CONCLUSION: Our comparison of complementary but distinct aspects of chemotherapy toxicity identified important longitudinal differences in fatigue and neuropathy by age and PS that are missed by the traditional maximum grade approach. Clinical trial identification number: NCT00003117 (CALGB 9730) IMPLICATIONS FOR PRACTICE: The traditional maximum grade approach ignores persistent low-grade adverse events (AEs) and changes over time. This toxicity over time analysis of fatigue and neuropathy during chemotherapy for advanced non-small cell lung cancer demonstrates how to use longitudinal methods to comprehensively characterize AEs over time by age and performance status (PS). We identified important longitudinal differences in fatigue and neuropathy that are missed by the maximum grade approach. This new information about how older adults and patients with PS 2 experience these toxicities longitudinally may be used clinically to improve discussions about treatment options and what to expect to inform shared decision making and symptom management.

Characterization of Sentinel Lymph Node Immune Signatures and Implications for Risk Stratification for Adjuvant Therapy in Melanoma.

BACKGROUND: Although sentinel lymph node (SLN) biopsy is a standard procedure used to identify patients at risk for melanoma recurrence, it fails to risk-stratify certain patients accurately. Because processes in SLNs regulate anti-tumor immune responses, the authors hypothesized that SLN gene expression may be used for risk stratification. METHODS: The Nanostring nCounter PanCancer Immune Profiling Panel was used to quantify expression of 730 immune-related genes in 60 SLN specimens (31 positive [pSLNs], 29 negative [nSLNs]) from a retrospective melanoma cohort. A multivariate prediction model for recurrence-free survival (RFS) was created by applying stepwise variable selection to Cox regression models. Risk scores calculated on the basis of the model were used to stratify patients into low- and high-risk groups. The predictive power of the model was assessed using the Kaplan-Meier and log-rank tests. RESULTS: During a median follow-up period of 6.3 years, 20 patients (33.3%) experienced recurrence (pSLN, 45.2% [14/31] vs nSLN, 20.7% [6/29]; p = 0.0445). A fitted Cox regression model incorporating 12 genes accurately predicted RFS (C-index, 0.9919). Improved RFS was associated with increased expression of TIGIT (p = 0.0326), an immune checkpoint, and decreased expression of CXCL16 (p = 0.0273), a cytokine important in promoting dendritic and T cell interactions. Independent of SLN status, the model in this study was able to stratify patients into cohorts at high and low risk for recurrence (p < 0.001, log-rank). CONCLUSIONS: Expression profiles of the SLN gene are associated with melanoma recurrence and may be able to identify patients as high or low risk regardless of SLN status, potentially enhancing patient selection for adjuvant therapy.

Variable Learning Curve of Basic Rigid Bronchoscopy in Trainees.

BACKGROUND: Despite increased use of rigid bronchoscopy (RB) for therapeutic indications and recommendations from professional societies to use performance-based competency, an assessment tool has not been utilized to measure the competency of trainees to perform RB in clinical settings. OBJECTIVES: The aim of the study was to evaluate a previously developed assessment tool - Rigid Bronchoscopy Tool for Assessment of Skills and Competence (RIGID-TASC) - for determining the RB learning curve of interventional pulmonary (IP) trainees in the clinical setting and explore the variability of learning curve of trainees. METHODS: IP fellows at 4 institutions were enrolled. After preclinical simulation training, all RBs performed in patients were scored by faculty using RIGID-TASC until competency threshold was achieved. Competency threshold was defined as unassisted RB intubation and navigation through the central airways on 3 consecutive patients at the first attempt with a minimum score of 89. A regression-based model was devised to construct and compare the learning curves. RESULTS: Twelve IP fellows performed 178 RBs. Trainees reached the competency threshold between 5 and 24 RBs, with a median of 15 RBs (95% CI, 6-21). There were differences among trainees in learning curve parameters including starting point, slope, and inflection point, as demonstrated by the curve-fitting model. Subtasks that required the highest number of procedures (median = 10) to gain competency included ability to intubate at the first attempt and intubation time of <60 s. CONCLUSIONS: Trainees acquire RB skills at a variable pace, and RIGID-TASC can be used to assess learning curve of IP trainees in clinical settings.

Effect of cryomilling time on microstructure evolution and hardness of cryomilled AZ31 powders.

The synthesis of nanostructured AZ31 powder by cryomilling was studied in this paper. The microstructural evolution during cryomilling, including the changes of particle morphology and internal grain size, was characterized via optical microscopy, SEM, TEM and XRD. Observations during the cryomilling produced four main findings. Firstly, cryomilling can refine the grains of AZ31 particles down to 100 nm after around 1 h milling and the minimum average grain size of about 30 nm was reached when the cryomilling time was extended to 6 h or longer. Secondly, cold welding played a dominant role in the early stage of cryomilling, while fracture took place in the late stage and surpassed cold welding. The former led to a particle size increase while the latter decreased the particle size. The minimum average particle size after 6 h cryomilling was approximately 26 µm. Thirdly, a few particles were agglomerated with other particles and could not be processed by cryomilling due to cold welding. Finally, after cryomilling 6 h and longer times, the hardness reached 162 HV which was much higher than other values reported in AZ31 alloy studies.

Lung Cancer Screening Eligibility and Use: A Population Health Perspective of One Community.

BACKGROUND Low-dose chest CT (LDCT) is the only effective screening test for lung cancer. Annual lung cancer screening (LCS) is recommended by the US Preventive Services Task Force (USPSTF) for individuals at high risk for primary lung neoplasm.METHODS We retrospectively identified patients receiving LCS from January 2016 through March 2018 whose residential addresses were within our health center's county. We estimated driving distance from the patient's address to our health center and obtained sociodemographic characteristics from the electronic health record (EHR). The census-tract-level LCS-eligible population size was estimated, and their population characteristics determined via US Census Bureau, Centers for Disease Control and Prevention (CDC), and Behavioral Risk Factor Surveillance System (BRFSS) data. The Cochran-Mantel-Haenszel test was used to determine differences amongst the LCS-eligible and LCS-enrolled populations. Multivariable regression was used to determine the effects of sociodemographic characteristics on LCS eligibility.RESULTS There was modest correlation between census-tract-level LCS-eligible population size and LCS enrollment (r = 0.68, P < .001). 5.9% (364/6185) of the estimated LCS-eligible population in our county received LCS, with census-tract LCS rates ranging from 1.5% to 12.5%. Nonwhite race status (Hispanic and African American) was associated with decreased likelihood of LCS enrollment compared to White race (OR = 95% CI, 0.765 [0.61, 0.95] and 0.031 [0.008, 0.124], respectively). Older age, Medicaid, and uninsured statuses were positively correlated with LCS eligibility (P ≤ .01).LIMITATIONS This analysis comprises a single county. Other LCS facilities within our health system in neighboring counties, as well as individuals receiving LCS outside of our health system, are not captured.CONCLUSIONS The uptake of LCS remains low, with disproportionately lower screening rates amongst Hispanic and African American populations. Medicaid and uninsured patients in our community are also more likely to be LCS-eligible. These populations may be targets for interventions aimed at increasing LCS awareness and uptake.

Clinical Factors Affecting Survival in Pediatric Vascular Tumors of the Head and Neck.

Clinical factors associated with the behavior and outcomes of nonbenign, head, and neck vascular tumors in children are not well described. Our aim is to provide descriptive information and identify prognostic factors associated with lower overall survival for children with these types of tumors. A retrospective cohort study was performed using the SEER database (years 1973-2015). Children aged 18 years and under with the diagnosis of a vascular tumor with locally aggressive or borderline and malignant behavior, classified by ICD-O-3, within the head and neck were included. Vascular tumors with benign behavior as classified by ISSVA were excluded. One hundred forty-eight children were identified. Mean age was 9.9 years (SD = 6.4). A gender predilection was noted with more males affected, female (37.8%) and male (62.2%), P = 0.0031. Majority of the children were white (79.4%) and angiosarcoma was the most common histologic subtype (68.2%). Children had a significantly better overall survival than adults with head and neck vascular tumors, P < 0.0001. Univariate and multivariate analysis did not reveal any factors with significant association to overall survival. Vascular tumors in the head and neck in children most commonly affect males and white children, with angiosarcoma as the most common histologic subtype. Children seem to have a more favorable overall survival compared to adults.

Clinical and radiographic predictors of successful therapeutic bronchoscopy for the relief of malignant central airway obstruction.

BACKGROUND: Malignant central airway obstruction (CAO) occurs in approximately 20-30% of patients with lung cancer and is associated with debilitating symptoms and poor prognosis. Multimodality therapeutic bronchoscopy can relieve malignant CAO, though carries risk. Evidence to guide clinicians regarding which patients may benefit from such interventions is sparse. We aimed to assess the clinical and radiographic predictors associated with therapeutic bronchoscopy success in relieving malignant CAO. METHODS: We reviewed all cases of therapeutic bronchoscopy performed for malignant CAO at our institution from January 2010-February 2017. Therapeutic bronchoscopy success was defined as establishing airway patency of > 50%. Patient demographics and baseline characteristics, oncology history, degree of airway obstruction, procedural interventions, and complications were compared between successful and unsuccessful groups. Univariate and multivariate logistic regression identified the significant clinical and radiographic predictors for therapeutic success. The corresponding simple and conditional odds ratio were calculated. A time-to-event analysis with Kaplan-Meier plots was performed to estimate overall survival. RESULTS: During the study period, 301 therapeutic bronchoscopies were performed; 44 (14.6%) were considered unsuccessful. Factors associated with success included never vs current smoking status (OR 5.36, 95% CI:1.45-19.74, p = 0.010), patent distal airway on CT imaging (OR 15.11, 95% CI:2.98-45.83, p < 0.0001) and patent distal airway visualized during bronchoscopy (OR 10.77, 95% CI:3.63-31.95, p < 0.001) in univariate analysis. Along with patent distal airway on CT imaging, increased time from radiographic finding to therapeutic bronchoscopy was associated with lower odds of success in multivariate analysis (OR 0.96, 95% CI:0.92-1.00, p = 0.048). Median survival was longer in the successful group (10.2 months, 95% CI:4.8-20.2) compared to the unsuccessful group (6.1 months, 95% CI:2.1-10.8, log rank p = 0.015). CONCLUSIONS: Predictors associated with successful therapeutic bronchoscopy for malignant CAO include distal patent airway visualized on CT scan and during bronchoscopy. Odds of success are higher in non-smokers, and with decreased time from radiographic finding of CAO to intervention.

The Role of Reconstructive Surgery After Skeletal and Soft Tissue Sarcoma Resection.

BACKGROUND: Skeletal and soft tissue reconstruction after sarcoma resection remains challenging. The use of advanced reconstructive techniques has been shown to improve function and increase rates of limb salvage. This study aims to analyze the utilization of plastic surgery within a multidisciplinary team approach after sarcoma resection at Duke University Medical Center from 2001 to 2014. METHODS: Medical records were reviewed to determine procedure type, postoperative complications, and tumor recurrence. Observations were stratified by oncologic diagnosis, anatomic location, and procedure type. Patients were excluded if final pathology was not indicative of sarcoma, if resection or reconstruction was not performed at our institution, if resection preceded reconstruction by greater than 60 days, or if no follow-up was recorded within 3 months. RESULTS: Of the 747 patients who met the inclusion criteria, 116 underwent reconstructive surgery. Tumor location was associated with a need for surgical reconstruction. Patients with upper (P = 0.0073) or lower (P = 0.0265) extremity tumors had a higher occurrence of plastic surgery involvement. Patients with a history of operative interventions had a higher likelihood of reconstructive surgery after oncologic resection (odds ratio, 1.649; P = 0.019). Neoadjuvant radiotherapy was associated with an increased likelihood of reconstructive plastic surgery after sarcoma resection (odds ratio, 2.131; P = 0.0004). CONCLUSIONS: Understanding the factors that necessitate reconstructive plastic surgery after sarcoma resection can enhance coordination of care within a multidisciplinary sarcoma center and leading to improved patient outcomes, including rates of limb salvage, as well as functionality and esthetic results.

Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction.

We use a combination of classical molecular dynamics simulation and neutron diffraction to identify the atomic structure of five different Mg-Zn-Ca bulk metallic glasses, covering a range of compositions with substantially different behaviour when implanted in vitro. There is very good agreement between the structures obtained from computer simulation and those found experimentally. Bond lengths and the total correlation function do not change significantly with composition. The zinc and calcium bonding shows differences between composition: the distribution of Zn-Ca bond lengths becomes narrower with increasing Zn content, and the preference for Zn and Ca to avoid bonding to themselves or each other becomes less strong, and, for Zn-Ca, transforms into a positive preference to bond to each other. This transition occurs at about the same Zn content at which the behaviour on implantation changes, hinting at a possible structural connection. A very broad distribution of Voronoi polyhedra are also found, and this distribution broadens with increasing Zn content. The efficient cluster packing model, which is often used to describe the structure of bulk metallic glasses, was found not to describe these systems well.

Duplicated antibiotic resistance genes reveal ongoing selection and horizontal gene transfer in bacteria.

Horizontal gene transfer (HGT) and gene duplication are often considered as separate mechanisms driving the evolution of new functions. However, the mobile genetic elements (MGEs) implicated in HGT can copy themselves, so positive selection on MGEs could drive gene duplications. Here, we use a combination of modeling and experimental evolution to examine this hypothesis and use long-read genome sequences of tens of thousands of bacterial isolates to examine its generality in nature. Modeling and experiments show that antibiotic selection can drive the evolution of duplicated antibiotic resistance genes (ARGs) through MGE transposition. A key implication is that duplicated ARGs should be enriched in environments associated with antibiotic use. To test this, we examined the distribution of duplicated ARGs in 18,938 complete bacterial genomes with ecological metadata. Duplicated ARGs are highly enriched in bacteria isolated from humans and livestock. Duplicated ARGs are further enriched in an independent set of 321 antibiotic-resistant clinical isolates. Our findings indicate that duplicated genes often encode functions undergoing positive selection and horizontal gene transfer in microbial communities.

Atezolizumab Before and After Chemoradiation for Unresectable Stage III Non-Small Cell Lung Cancer: A Phase II Nonrandomized Controlled Trial.

Importance: Outcomes for patients with unresectable stage III non-small cell lung cancer (NSCLC) treated with chemoradiation therapy (CRT) have improved with adjuvant immune checkpoint inhibitors, with a reported 5-year overall survival benefit of approximately 10% for adjuvant durvalumab vs placebo after completion of CRT without progression and with preserved performance status. Starting atezolizumab prior to CRT may allow more patients to benefit from immunotherapy. Objective: To evaluate clinical outcomes of patients treated with atezolizumab before and after CRT for unresectable stage III NSCLC. Design, Setting, and Participants: This single-cohort, phase II, nonrandomized controlled trial was conducted at 11 US sites. Patients with pathologically confirmed, unresectable stage III NSCLC who were treatment naive and had good performance status were enrolled between January 3, 2018, and July 24, 2019. Data were locked on March 21, 2023. Interventions: Patients received four 21-day cycles of atezolizumab, 1200 mg intravenously, with therapy administered on day 1 of each cycle. Patients not experiencing tumor progression continued to CRT (60 Gy to involved fields) concurrent with weekly carboplatin area under the curve of 2 and paclitaxel, 50 mg/m2, followed by planned consolidation carboplatin area under the curve of 6 and paclitaxel, 200 mg/m2, for two 21-day cycles. Patients not experiencing progression continued atezolizumab, 1200 mg, every 21 days to complete 1 year of therapy. Main Outcomes and Measures: The primary end point was the disease control rate at 12 weeks. Secondary end points were progression-free survival, overall survival, overall response rate, safety, and translational science end points. Results: A total of 62 patients (median [range] age, 63.9 [38.1-86.5] years; 32 female [51.6%]) were enrolled and received at least 1 dose of atezolizumab. The disease control rate at 12 weeks was 74.2% (80% CI, 65.7%-81.4%). Median progression-free survival was 30.0 months (95% CI, 15.8 to not evaluable), and the median overall survival was not reached. The overall survival rate at 24 months was 73.7% (95% CI, 63.4%-85.7%), and the overall response rate was 66.2%. Seventeen patients (27.4%) experienced grade 3 or higher immune-related adverse events, including 1 with grade 5 pneumonitis and 1 with grade 4 Guillain-Barré syndrome. Thirty patients (48.4%) experienced grade 3 or higher treatment-related adverse events. Conclusions and Relevance: These findings suggest that neoadjuvant atezolizumab merits further study based on safety and encouraging outcomes. Trial Registration: ClinicalTrials.gov Identifier: NCT03102242.

Seedless wet synthesis of copper-twinned nanocrystals.

The wet synthesis of copper (Cu)-twinned nanostructures often requires the addition of noble metal seeds, as twinned Cu seeds are prone to oxidative etching, which inevitably introduces other metal species. In this study, a universal and seedless wet method is proposed for the synthesis of various Cu-twinned nanostructures, such as large Cu decahedrons (with sizes up to 300 nm), singly twinned Cu right bipyramids, and Cu nanorods. The amount of chloride ions (Cl-) and oleylamine and an optimal heating rate at the initial stage were proven to be crucial in this synthesis. Theoretical results revealed that the amount of Cl- could adjust the Gibbs free energy of Cu seeds by promoting the dissociation of oleylamine, which, in turn, determined the structure of thermodynamically favorable seeds based on the thermodynamic model. To the best of our knowledge, this is the first report on large Cu decahedrons and singly twinned Cu right bipyramids. Moreover, they both showed strong localized surface plasmon resonance in the near-infrared region. The photothermal conversion efficiency of large Cu decahedrons increased up to 52.9% upon 808 nm laser irradiation, which is the highest value ever reported for Cu nanocrystals.

Study on Corrosion Behavior and Mechanism of Ultrahigh-Strength Hot-Stamping Steel Based on Traditional and Compact Strip-Production Processes.

Hot-stamping steel is a type of high-strength steel that is mainly used in key safety components such as the front and rear bumpers, A-pillars, and B-pillars of vehicles. There are two methods of producing hot-stamping steel, i.e., the traditional process and the near net shape of compact strip production (CSP) process. To assess the potential risks of producing hot-stamping steel using CSP, the microstructure and mechanical properties, and especially the corrosion behavior were focused on between the traditional and CSP processes. The original microstructure of hot-stamping steel produced by the traditional process and the CSP process is different. After quenching, the microstructures transform into full martensite, and their mechanical properties meet the 1500 MPa grade. Corrosion tests showed that the faster the quenching speeds, the smaller the corrosion rate of the steel. The corrosion current density changes from 15 to 8.6 µA·cm-2. The corrosion resistance of hot-stamping steel produced by the CSP process is slightly better than that of traditional processes, mainly since the inclusion size and distribution density of CSP-produced steel were both smaller than those of the traditional process. The reduction of inclusions reduces the number of corrosion sites and improves the corrosion resistance of steel.

Multi-Scale Microstructural Tailoring and Associated Properties of Press-Hardened Steels: A Review.

High-strength press-hardened steels (PHS) are highly desired in the automotive industry to meet the requirement of carbon neutrality. This review aims to provide a systematic study of the relationship between multi-scale microstructural tailoring and the mechanical behavior and other service performance of PHS. It begins with a brief introduction to the background of PHS, followed by an in-depth description of the strategies used to enhance their properties. These strategies are categorized into traditional Mn-B steels and novel PHS. For traditional Mn-B steels, extensive research has verified that the addition of microalloying elements can refine the microstructure of PHS, resulting in improved mechanical properties, hydrogen embrittlement resistance, and other service performance. In the case of novel PHS, recent progress has principally demonstrated that the novel composition of steels coupling with innovative thermomechanical processing can obtain multi-phase structure and superior mechanical properties compared with traditional Mn-B steels, and their effect on oxidation resistance is highlighted. Finally, the review offers an outlook on the future development of PHS from the perspective of academic research and industrial applications.

Phase Transformation Behaviors of Medium Carbon Steels Produced by Twin Roll Casting and Compact Strip Production Processes.

Medium carbon steels have been widely used in the fields of tool and die manufacturing due to their outstanding hardness and wear resistance. In this study, microstructures of 50# steel strips fabricated by twin roll casting (TRC) and compact strip production (CSP) processes were analyzed to investigate the influences of solidification cooling rate, rolling reduction, and coiling temperature on composition segregation, decarburization, and pearlitic phase transformation. The results show that a partial decarburization layer with a thickness of 13.3 µm and banded C-Mn segregation were observed in the 50# steel produced by CSP, leading to the banded distributions of ferrite and pearlite in the C-Mn poor regions and C-Mn rich regions, respectively. For the steel fabricated by TRC, owing to the sub-rapid solidification cooling rate and short processing time at high temperatures, neither apparent C-Mn segregation nor decarburization was observed. In addition, the steel strip fabricated by TRC has higher pearlite volume fractions, larger pearlite nodule sizes, smaller pearlite colony sizes and interlamellar spacings due to the co-influence of larger prior austenite grain size and lower coiling temperatures. The alleviated segregation, eliminated decarburization and large volume fraction of pearlite render TRC a promising process for medium carbon steel production.

The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing.

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid-state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel-based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed.