MCrAlX powder compositions (M = Ni,Co and X = Y, Hf, Si or combination) are often thermally sprayed via vacuum plasma spray (VPS), low pressure plasma spray (LPPS) or high velocity oxy-fuel to ...produce high temperature oxidation and hot corrosion resistant bond coats for thermal barrier coatings (TBCs). Cold spray technology is currently considered as a promising alternative to the traditional thermal spray solutions, having the advantage of delivering oxide-free and very dense metallic coatings at relatively lower costs compared to VPS and LPPS. NiCoCrAlY and NiCoCrAlYHfSi bond coats were deposited using a high pressure cold spray system and the influence of feedstock properties on the deposited bond coats were investigated. To improve NiCoCrAlYHfSi bond coat deposition, laser assisted cold spray (LACS) was employed. The results show that LACS can be successfully used to deposit this particular powder while eliminating nozzle erosion and low deposition efficiency disadvantages observed with conventional cold spray. To identify the optimal LACS setup for deposition of dense and uniform coatings, different laser/spray jet configurations were examined. TBCs with bond coats sprayed at the optimal configuration were assessed isothermally at 1150 °C in air for up to 500 h, and the results showed formation of a thermally grown oxide layer composed of predominantly Al
2
O
3
with embedded small clusters of Hf-Y-rich oxides.
The cold spray deposition behavior of a CrMnCoFeNi High Entropy Alloy (HEA) powder was investigated using N
2
as the process gas on three different substrates of Al6061, mild steel and Hastelloy X. ...Well adhering and dense coatings were obtained at 950 °C and 5 MPa of propelling gas temperature and pressure, respectively. Microstructure and microhardness analyses showed significantly deformed particles in dense coatings on all three substrates, with imperfect inter-particle bonding. Laser-assisted cold spray (LACS) was used to enhance the deposition behavior of the CrMnCoFeNi powder and inter-particle bonding. Electron channeling contrast imaging analyses of coatings showed that linear structures similar to twinning are formed in the deposited particles. X-ray diffraction analysis showed that the single-phase face center cubic structure of CrMnCoFeNi powder is retained in the coatings, although peak broadening associated with grain refinement was observed. Comparison of the physical parameters (i.e., particle velocity and temperature at impact) required for deposition of CrMnCoFeNi powder with those required for conventional alloys revealed that the deposition of this HEA is significantly more challenging due to solid solution strengthening and excellent work hardenability.
Since the first cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, there have been challenges recognizing the clinical features of SARS-CoV-2 and identifying therapeutic ...options. This has been compounded by viral mutations that affect clinical response and primary epidemiological indicators. Multiple variants of SARS-CoV-2 have been identified and classified on the basis of nomenclature implemented by scientific organizations and the World Health Organisation (WHO). A total of five variants of concern (VOCs) have been identified to date. The present study aimed to analyse clinical and epidemiological features of each variant. Based on these characteristics, predictions were made about potential future evolution. Considering the time and location of SARS-CoV-2 VOC emergence, it was hypothesised that mutations were not due to pressure caused by the vaccines introduced in December 2020 but were dependent on natural characteristics of the virus. In the process of adapting to the human body, SARS-CoV-2 is expected to undergo evolution to become more contagious but less deadly. SARS-CoV-2 was hypothesized to continue spread through isolated epidemic outbreaks due to the unimmunized population, mostly unvaccinated children and adults, and for coronaviruses to continue to present a public health problem.
Structural reactive material (SRM) is consolidated from a fine granular mixture of reactive materials towards the mixture theoretical maximum density with little porosity, thus bearing both high ...energy density and mechanical strength. A reactive hot spot concept was investigated for fine fragmentation of a SRM solid under explosive loading to augment air blast through rapid reaction of fine SRM fragments. In this concept, micro‐sized reactive materials were distributed in a fuel‐rich SRM solid, such as MoO3 particles consolidated in a particulate aluminum base in 10Al+MoO3. Intermetallic reactions of micro‐sized MoO3 and nearby Al under explosive loading created heat and gas products to form microscale hot spots that initiated local fractures leading to fine fragments of the rest of Al. The SRM solid was made of a thick‐walled cylindrical casing, containing a high explosive in a detonation pressure range of 25–34 GPa with a casing‐to‐explosive mass ratio of 1.78. Experiments in a cylindrical chamber demonstrated the presence of a large amount of fine SRM fragments, whose reaction promptly after detonation significantly enhanced the primary and near field blast wave, as compared to the results from a baseline pure Al‐cased charge, thus indicating the feasibility of the concept.
The renin-angiotensin system (RAS) is one of the biggest challenges of cardiovascular medicine. The significance of the RAS in the chronic progression of SARS-CoV-2 infection and its consequences is ...one of the topics that are currently being mostly discussed. SARS-CoV-2 undermines the balance between beneficial and harmful RAS pathways. The level of soluble ACE2 and membrane-bound ACE2 are both upregulated by the endocytosis of the SARS-CoV-2/ACE2 complex and the tumor necrosis factor (TNF)-α-converting enzyme (ADAM17)-induced cleavage. Through the link between RAS and the processes of proliferation, the processes of fibrous remodelling of the myocardium are initiated from the acute phase of the disease, continuing into the long COVID stage. In the long term, RAS dysfunction may cause an impairment of its beneficial effects leading to thromboembolic processes and a reduction in perfusion of target organs. The main aspects of ACE2-a key pathogenic role in COVID-19 as well as the mechanisms of RAS involvement in COVID cardiovascular injuries are studied. Therapeutic directions that can be currently anticipated in relation to the various pathogenic pathways of progression of cardiovascular damage in patients with longCOVID have also been outlined.
Objectives: SARS-CoV-2 virus detection on nasopharyngeal specimens to infected individuals was a challenge for the COVID-19 pandemic outbreak. The aim of the study was to compare the performance of ...antigenic detection of SARS-CoV-2 in nasopharyngeal samples using an immunochromatographic method with molecular detection via qRT-PCR. Materials and Methods: 47 nasopharyngeal exudates were collected from suspected COVID-19 cases. The samples were performed both with the qualitative immuno-chromatographic method for S protein detection in the SARS-CoV-2 structure, fluorescent labelled anti-protein S antibodies and by qRT-PCR test for the qualitative detection of the screening gene E and the specific ORF1ab region of the RNA-SARS-CoV-2. Results: There was a good correlation between the positive antigen tests and the positive PCR assays measured through threshold cycle ORF1ab region (Ct orf). A better correlation was obtained between the antigen test results and the positive qRT-PCR tests when including patients with Ct orf below 25. Conclusions: Antigen testing is helpful for symptomatic people, especially during infectious period. A positive test has a high predictive value for infection, while a negative antigen test result via immuno-chromatography must be confirmed by a qRT-PCR test.
Pulmonary fibrosis, a critical outcome of chronic inflammatory diseases, has gained prominence in the context of post-coronavirus (post-COVID-19) complications. This review delves into the ...multifaceted landscape of post-COVID-19 pulmonary fibrosis, elucidating the intricate molecular mechanisms underlying its pathogenesis and highlighting promising therapeutic avenues. Examining the aftermath of severe acute respiratory syndrome-2 (SARS-CoV-2) infection, the review reveals key signaling pathways implicated in the fibrotic cascade. Drawing parallels with previous coronavirus outbreaks enhances our understanding of the distinctive features of post-COVID-19 fibrosis. Antifibrotic drugs, like pirfenidone and nintedanib, take center stage; their mechanisms of action and potential applications in post-COVID-19 cases are thoroughly explored. Beyond the established treatments, this review investigates emerging therapeutic modalities, including anti-interleukin agents, immunosuppressants, and experimental compounds, like buloxybutide, saracatinib, sirolimus, and resveratrol. Emphasizing the critical importance of early intervention, this review highlights the dynamic nature of post-COVID-19 pulmonary fibrosis research. In conclusion, the synthesis of current knowledge offers a foundation for advancing our approaches to the prevention and treatment of these consequential sequelae of COVID-19.
Hypersensitivity pneumonitis is classified in the interstitial lung disease group, being caused by inhalation exposure to sensitized allergen. Exposure to inhalant allergens is often significant in ...the workplace, being favoured by the long duration of time spent at work, air circulation, and alveolar hyperventilation during high physical efforts and technological processes involved. Identifying the causative agents of Hypersensitivity pneumonitis is not always easy and symptoms often appear insidiously, after long periods of exposure, which can delay diagnosis. In addition, diagnostic tests do not always provide rapid positive results or involve invasive explorations that cannot be applied or are not accepted by patients. We exemplify these findings with a case study of Hypersensitivity pneumonitis following exposure to fish products and derivatives. Although initiation of treatment and cessation of exposure may improve symptoms and reverse pulmonary interstitial changes, exacerbations and rapid progression are not usual developmental pathways. Worker sensitization, effective ventilation of workplaces, wearing protective equipment (especially protective masks adapted to the type and size of particles released) and regular assessment of employees are the main measures to reduce the risk of most respiratory diseases.
We present studies on parallel nanoscale patterning of piezoelectrics/ferroelectrics via deposition through a nanostencil. Unlike other processes reported for oxide nanostructuring, we selectively ...deposit the material, directly, by interposing a nanosieve between the substrate and the deposition source. We show that this selective deposition can be realized even with materials as complex as perovskite oxides, both at room temperature and at high temperature. We elaborate on and analyze the performance of the nanostenciling approach for the growth of barium titanate BaTiO
3 on strontium titanate SrTiO
3(1
0
0). The patterned structures of ferroelectric materials are characterized by X-ray diffraction and imaged locally by scanning probe microscopy in piezoresponse mode to individually probe their functionality.
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