Controlling the length scale and distribution of the ductile phase in metallic glass composites through friction stir processing.

We demonstrate the refinement and uniform distribution of the crystalline dendritic phase by friction stir processing (FSP) of titanium based in situ ductile-phase reinforced metallic glass composite. The average size of the dendrites was reduced by almost a factor of five (from 24 µm to 5 µm) for the highest tool rotational speed of 900 rpm. The large inter-connected dendrites become more fragmented with increased circularity after processing. The changes in thermal characteristics were measured by differential scanning calorimetry. The reduction in crystallization enthalpy after processing suggests partial devitrification due to the high strain plastic deformation. FSP resulted in increased hardness and modulus for both the amorphous matrix and the crystalline phase. This is explained by interaction of shear bands in amorphous matrix with the strain-hardened dendritic phase. Our approach offers a new strategy for microstructural design in metallic glass composites.

Towards Sustainability: An Eco-Friendly Approach for Durable Anti-Icing Superhydrophobic Surfaces.

The growing interest in flexible superhydrophobic surfaces extends beyond various practical applications like solar panels, flexible electronics, etc. This study introduces a cost-effective and environmentally friendly method to create a durable, flexible, and optically semi-transparent superhydrophobic film with an extreme anti-icing character. The prestrained polydimethylsiloxane film subjected to biofuel-based flame treatment under controlled conditions induces microwrinkles with a superimposed cluster of nanoparticles while maintaining surface flexibility and transparency. This meticulous process enhances surface roughness, achieving superhydrophobic characteristics (θ > 165˚) with a remarkably low tilting angle (<3˚) with adhesion against water <2 µN (lower than Lotus leaf). The films applied over solar panels result in <1% voltage drop within 5 s due to effective cleaning under simulated rain. The remarkable anti-icing performance of the developed film is characterized by ice adhesion <25 kPa over 50 icing/de-icing cycles attributed to the presence of nanoclusters. The films displayed exceptional resilience and sustained efficacy under prolonged exposure to harsh external environments. These superhydrophobic films, characterized by flexibility, durability, and transparency, present promising opportunities for fabricating structures, even with intricate geometries. These findings imply a significant stride in the practical utilization of superhydrophobic surfaces, demonstrating their potential in diverse real-world applications.

Tribological Behavior of Bioinspired Surfaces.

Energy losses due to various tribological phenomena pose a significant challenge to sustainable development. These energy losses also contribute toward increased emissions of greenhouse gases. Various attempts have been made to reduce energy consumption through the use of various surface engineering solutions. The bioinspired surfaces can provide a sustainable solution to address these tribological challenges by minimizing friction and wear. The current study majorly focuses on the recent advancements in the tribological behavior of bioinspired surfaces and bio-inspired materials. The miniaturization of technological devices has increased the need to understand micro- and nano-scale tribological behavior, which could significantly reduce energy wastage and material degradation. Integrating advanced research methods is crucial in developing new aspects of structures and characteristics of biological materials. Depending upon the interaction of the species with the surrounding, the present study is divided into segments depicting the tribological behavior of the biological surfaces inspired by animals and plants. The mimicking of bio-inspired surfaces resulted in significant noise, friction, and drag reduction, promoting the development of anti-wear and anti-adhesion surfaces. Along with the reduction in friction through the bioinspired surface, a few studies providing evidence for the enhancement in the frictional properties were also depicted.

Common Noninfectious Complications Following Lung Transplantation.

According to the Scientific Registry of Transplant Recipients, both transplant volume and survival among lung transplant recipients are improving over time. However, the outcomes of lung transplantation remain challenged by multiple thoracic and extrathoracic complications. With improving lung transplant survival, patients experience prolonged exposure to chronic immunosuppressive agents that can lead to multiple infectious and noninfectious complications. This article focuses on most common noninfectious complications with significant clinical impact.

Transformation of pancreatic nonfunctioning neuroendocrine tumor into metastatic insulinoma: A rare case report.

Pancreatic neuroendocrine tumors can be classified as functional or nonfunctional based on hormone secretion. Management of each entity is different, with nonfunctional tumors being treated with traditional chemotherapy while functional tumors respond well to antihormonal therapy and immunologic agents. The conversion of one nonfunctional tumor into a functional tumor is an exceedingly rare event that complicates the overall management of these patients. In this report, we present the case of a 73-year-old woman who developed the conversion from a nonfunctional into a functional tumor and discuss the management options considered.

Acute Dyspnea After Lung Transplantation: A Twisted Tale.

CASE PRESENTATION: A 67-year-old woman developed sudden-onset severe dyspnea 24 h after a bilateral sequential lung transplant for COPD. She had an uneventful surgery performed on cardiopulmonary bypass support. She required two units of packed RBCs as well as fresh frozen plasma during the surgery. She was successfully extubated within 12 h of surgery. Her primary graft dysfunction score was grade 2, 1, and 1 at 0, 12, and 24 h, respectively. Approximately 24 h after the procedure, she complained of increasing shortness of breath without fever, chills, cough, or pleuritic chest pain.

Nonallograft Complications of Lung Transplantation.

Long-term exposure to immunosuppressive therapy may exacerbate pre-existing medical comorbidities or result in the development of new chronic medical conditions after lung transplantation. This article focuses on common nonallograft complications with the highest impact on short- and long-term outcomes after transplantation. These include diabetes mellitus, hypertension, dyslipidemia, kidney disease (acute and chronic), and malignancy. We discuss evidence-based strategies for the prevention, diagnosis, and management of these nonallograft complications in this article.

Malakoplakia Presenting as a Lung Mass in a Lung Transplant Recipient: Case Report.

Lung nodules or masses due to a variety of malignant or benign conditions such as opportunistic infections are observed after lung transplant. Malakoplakia is a rare complication in immunocompromised patients. Here we describe the clinical course and management of a lung transplant recipient with pulmonary malakoplakia and provide a review of the literature. To our knowledge, this is the first report of a case of pulmonary malakoplakia due to Escherichia coli infection in a lung allograft.

Early postoperative complications in lung transplant recipients.

Lung transplantation has become an established therapy for end-stage lung diseases. Early postoperative complications can impact immediate, mid-term, and long-term outcomes. Appropriate management, prevention, and early detection of these early postoperative complications can improve the overall transplant course. In this review, we highlight the incidence, detection, and management of these early postoperative complications in lung transplant recipients.

Geographic disparities in lung transplantation in the United States before and after the November 2017 allocation change.

BACKGROUND: The primary lung allocation unit was expanded from the donation service area to a 250-mile radius in 2017. Prior to the change, geographic disparities in donor lung availability impacted waitlist outcomes. We sought to determine if the new allocation system improved these disparities. METHODS: We conducted a retrospective cohort study comparing the 2-year period before and after the change. Donor lung availability was defined as the ratio of donor lungs to waitlist candidates in the primary allocation unit. Transplant centers were divided into quartiles by donor lung availability. Multivariable competing risk models were used to determine the association between lung availability and waitlist outcomes. Multivariable Cox proportional hazards models compared post-transplant survival. RESULTS: Prior to the allocation change, the unadjusted transplant rate at centers in the lowest and highest quartiles was 132 and 607 transplants per 100 waitlist years. Candidates in the lowest quartile of donor lung availability had a 61% adjusted lower transplantation rate compared to candidates in highest quartile (sub-hazard ratio [sHR]: 0.39, 95% confidence interval [CI]: 0.34-0.44). After the allocation change, the disparity decreased resulting in an unadjusted transplant rate of 141 and 309 among centers in the lowest and highest quartiles. Candidates in the lowest quartile had a 38% adjusted lower transplantation rate compared to those in the highest (sHR: 0.62, 95% CI: 0.57-0.68). There was no significant difference in 1-year post-transplant survival. CONCLUSIONS: Although the expansion of the primary allocation unit improved disparities in waitlist outcomes without any change in post-transplant survival, there still remain significant differences due to geography.

Advancements in the Additive Manufacturing of Magnesium and Aluminum Alloys through Laser-Based Approach.

Complex structures can now be manufactured easily utilizing AM technologies to meet the pre-requisite objectives such as reduced part numbers, greater functionality, and lightweight, among others. Polymers, metals, and ceramics are the few materials that can be used in AM technology, but metallic materials (Magnesium and Aluminum) are attracting more attention from the research and industrial point of view. Understanding the role processing parameters of laser-based additive manufacturing is critical to maximize the usage of material in forming the product geometry. LPBF (Laser powder-based fusion) method is regarded as a potent and effective additive manufacturing technique for creating intricate 3D forms/parts with high levels of precision and reproducibility together with acceptable metallurgical characteristics. While dealing with LBPF, some degree of porosity is acceptable because it is unavoidable; hot ripping and cracking must be avoided, though. The necessary manufacturing of pre-alloyed powder and ductility remains to be the primary concern while dealing with a laser-based additive manufacturing approach. The presence of the Al-Si eutectic phase in AlSi10Mg and AlSi12 alloy attributing to excellent castability and low shrinkage, attaining the most attention in the laser-based approach. Related studies with these alloys along with precipitation hardening and heat treatment processing were discussed. The Pure Mg, Mg-Al alloy, Mg-RE alloy, and Mg-Zn alloy along with the mechanical characteristics, electrochemical durability, and biocompatibility of Mg-based material have been elaborated in the work-study. The review article also summarizes the processing parameters of the additive manufacturing powder-based approach relating to different Mg-based alloys. For future aspects, the optimization of processing parameters, composition of the alloy, and quality of powder material used will significantly improve the ductility of additively manufactured Mg alloy by the LPBF approach. Other than that, the recycling of Mg-alloy powder hasn't been investigated yet. Meanwhile, the post-processing approach, including a homogeneous coating on the porous scaffolds, will mark the suitability in terms of future advancements in Mg and Al-based alloys.

One Year Into the Pandemic: Evolving COVID-19 Outcomes in Lung Transplant Recipients, a Single-center Experience.

In the early months of the coronavirus disease 2019 (COVID-19) pandemic, our center reported a mortality rate of 34% in a cohort of 32 lung transplant recipients with COVID-19 between March and May 2020. Since then, there has been evolving knowledge in prevention and treatments of COVID-19. To evaluate the impact of these changes, we describe the clinical presentation, management, and outcomes of a more recent cohort of lung transplant recipients during the second surge and provide a comparison with our first cohort. Methods: We conducted a retrospective cohort study that included all consecutive lung transplant recipients who tested positive for severe acute respiratory syndrome coronavirus 2 between November 2020 and February 28, 2021. We compared baseline demographics and major outcomes between the first- and second-surge cohorts. Results: We identified 47 lung transplant recipients (median age, 60; 51% female) who tested positive for severe acute respiratory syndrome coronavirus 2 between November 2020 and February 28, 2021. The current cohort had a higher proportion of patients with mild disease (34% versus 16%) and fewer patients with a history of obesity (4% versus 25%). Sixty-six percent (n = 31) required hospitalization and were treated with remdesivir (90%) and dexamethasone (84%). Among those hospitalized, 77% (n = 24) required supplemental oxygen, and 22% (n = 7) required invasive mechanical ventilation. The overall 90-d mortality decreased from 34% to 17% from the first cohort to the second (adjusted odds ratio, 0.26; 95% confidence interval, 0.08-0.85; P = 0.026). Conclusions: Although COVID-19-associated mortality rate in lung transplant recipients at our center has decreased over time, COVID-19 continues to be associated with significant morbidity and mortality.

Enhanced Biocorrosion Resistance and Cellular Response of a Dual-Phase High Entropy Alloy through Reduced Elemental Heterogeneity.

The leaching out of toxic elements from metallic bioimplants has serious repercussions, including allergies, peripheral neuritis, cancer, and Alzheimer's disease, leading to revision or replacement surgeries. The development of advanced structural materials with excellent biocompatibility and superior corrosion resistance in the physiological environment holds great significance. High entropy alloys (HEAs) with a huge compositional design space and outstanding mechanical and functional properties can be promising for bioimplant applications. However, microstructural heterogeneity arising from elemental segregation in these multiprinciple alloy systems is the Achilles heel in the development of next-generation HEAs. Here, we demonstrate a pathway to homogenize the microstructure of a biocompatible dual-phase HEA, comprising refractory elements, namely, MoNbTaTiZr, through severe surface deformation using stationary friction processing (SFP). The strain and temperature field during processing homogenized the elemental distribution, which was otherwise unresponsive to conventional annealing treatments. Nearly 15 min of the SFP treatment resulted in a significant elemental homogenization across dendritic and interdendritic regions, similar to a week-long annealing treatment at 1275 K. The SFP processed alloy showed a nearly six times higher biocorrosion resistance compared to its as-cast counterpart. X-ray photoelectron spectroscopy was used to investigate the nature of the oxide layer formed on the specimens. Superior corrosion behavior of the processed alloy was attributed to the formation of a stable passive layer with zirconium oxide as the primary constituent and higher hydrophobicity. Biocompatibility studies performed using the human mesenchymal stem cell line, showed higher viability for the processed HEA compared to its as-cast counterpart as well as conventional metallic biomaterials including stainless steel (SS316L) and titanium alloy (Ti6Al4V).

Treatment of Tracheobronchial Injuries: A Contemporary Review.

Tracheobronchial injury is a rare but a potentially high-impact event with significant morbidity and mortality. Common etiologies include blunt or penetrating trauma and iatrogenic injury that might occur during surgery, endotracheal intubation, or bronchoscopy. Early recognition of clinical signs and symptoms can help risk-stratify patients and guide management. In recent years, there has been a paradigm shift in the management of tracheal injury towards minimally invasive modalities, such as endobronchial stent placement. Although there are still some definitive indications for surgery, selected patients who meet traditional surgical criteria as well as those patients who were deemed to be poor surgical candidates can now be managed successfully using minimally invasive techniques. This paradigm shift from surgical to nonsurgical management is promising and should be considered prior to making final management decisions.

Ultrasonic cavitation erosion-corrosion behavior of friction stir processed stainless steel.

Cavitation erosion remains the primary cause of material degradation in fluid machinery components operating at high speed. Micro-jets/shock waves caused by implosion of bubbles on material surface results in significant material loss and premature failure of the components. The presence of corrosive medium further exuberates this effect, causing rapid degradation. Here, we demonstrate a novel pathway to control cavitation erosion-corrosion by tailoring the surface properties using submerged friction stir processing (FSP), a severe plastic deformation process. FSP parameters were varied over wide range of strain-rates to generate tailored microstructures. High strain-rate processing resulted in nearly single phase fine grained structure while low strain-rate processing resulted in phase transformation in addition to grain refinement. As-received and processed samples were subjected to ultrasonic cavitation in distilled water as well as in corrosive environment of 3.5% NaCl solution. Individual roles of cavitation erosion, corrosion and their synergistic effects were analyzed. Depending on the microstructure, processed samples showed nearly 4-6 times higher cavitation erosion resistance compared to as-received alloy. Superior cavitation erosion-corrosion resistance of processed samples was attributed to surface strengthening, higher strain-hardening ability and quick passivation kinetics. The results of current study could be potentially transformative in designing robust materials for hydro-dynamic applications.

Post-transplant lymphoproliferative disorder of the bladder in a lung transplant recipient.

Post-transplant lymphoproliferative disorder (PTLD) occurs in ~5% of solid organ and hematopoietic stem cell transplant recipients. We report a unique presentation of PTLD in the bladder of a lung transplant recipient. Our patient was a 62-year-old female who received a bilateral lung transplant for chronic obstructive pulmonary disease. She presented with fever, left-sided flank pain and foul-smelling urine consistent with urosepsis. An abdominal and pelvic computerized tomography revealed an irregular and nodular bladder wall thickening suspicious for urothelial neoplasm. Cystoscopy revealed multiple bladder masses and biopsy demonstrated non-Hodgkin lymphoma consistent with PTLD. She was treated with a reduction in immunosuppression followed by chemotherapy and achieved remission. PTLD in the lung transplant recipients has been described in the gut, respiratory tract, skin, liver and kidney but not in the bladder. This case highlights the need for maintaining a high clinical vigilance even when transplant recipients present with seemingly benign clinical complaints.

Does the obesity paradox predict functional outcome in intracerebral hemorrhage?

OBJECTIVEBeing overweight or mildly obese has been associated with a decreased risk of death or hospitalization in patients with cardiovascular disease. Similarly, overweight patients admitted to an intensive care unit (ICU) have improved survival up to 1 year after admission. These counterintuitive observations are examples of the "obesity paradox." Does the obesity paradox exist in patients with intracerebral hemorrhage (ICH)? In this study the authors examined whether there was an association between obesity and functional outcome in patients with ICH.METHODSThe authors analyzed 202 patients admitted to the neurological ICU (NICU) who were prospectively enrolled in the Columbia University ICH Outcomes Project between September 2009 and December 2012. Patients were categorized into 2 groups: overweight (body mass index [BMI] ≥ 25 kg/m2) and not overweight (BMI < 25 kg/m2). The primary outcome was defined as survival with favorable outcome (modified Rankin Scale [mRS] score 0-3) versus death or severe disability (mRS score 4-6) at 3 months.RESULTSThe mean age of the patients in the study was 61 years. The mean BMI was 28 ± 6 kg/m2. The mean Glasgow Coma Scale score was 10 ± 4 and the mean ICH score was 1.9 ± 1.3. The overall 90-day mortality rate was 41%. Among patients with a BMI < 25 kg/m2, 24% (17/70) had a good outcome, compared with 39% (52/132) among those with a BMI ≥ 25 kg/m2 (p = 0.03). After adjusting for ICH score, sex, do-not-resuscitate code status, and history of hypertension, being overweight or obese (BMI ≥ 25 kg/m2) was associated with twice the odds of having a good outcome compared with patients with BMI < 25 kg/m2 (adjusted odds ratio 2.05, 95% confidence interval 1.03-4.06, p = 0.04).CONCLUSIONSIn patients with ICH admitted to the NICU, being overweight or obese (BMI ≥ 25 kg/m2) was associated with favorable outcome after adjustment for established predictors. The reason for this finding requires further study.

Serial dobutamine stress echocardiography with Doppler assessment of the left internal thoracic artery graft after minimally invasive bypass for a patient with an orthotopic heart transplant.

Select patients who have undergone orthotopic heart transplantation with proximal left anterior disease may be candidates for minimally invasive direct coronary artery bypass surgery. Combining left internal thoracic artery transthoracic Doppler flow assessment with wall motion assessment during dobutamine stress echocardiography adds to the utility of this test by focusing attention on the graft's status as well as detecting ischemia due to cardiac allograft vasculopathy.