Experimental verification of a model describing the occupied volume by polymers in solution

A relation is proposed which yields the occupied volume by macromolecular chains in solution. The experimental verification of the model is carried out by a viscometric study of the ternary system polymer A/polymer B/solvent. More precisely the viscometric study permits the determination of the critical concentration c^** corresponding to the incipient overlap of spherical coils.     

Association of sleep duration and quality with immunological response after vaccination against severe acute respiratory syndrome coronavirus-2 infection

Growing evidence suggests that sleep could affect the immunological response after vaccination. The aim of this prospective study was to investigate possible associations between regular sleep disruption and immunity response after vaccination against coronavirus disease 2019 (COVID-19). In total, 592 healthcare workers, with no previous history of COVID-19, from eight major Greek hospitals were enrolled in this study. All subjects underwent two Pfizer–BioNTech messenger ribonucleic acid (mRNA) COVID-19 vaccine BNT162b2 inoculations with an interval of 21 days between the doses. Furthermore, a questionnaire was completed 2 days after each vaccination and clinical characteristics, demographics, sleep duration, and habits were recorded. Blood samples were collected and anti-spike immunoglobulin G antibodies were measured at 20 ± 1 days after the first dose and 21 ± 2 days after the second dose. A total of 544 subjects (30% males), with median (interquartile range [IQR]) age of 46 (38–54) years and body mass index of 24·84 (22.6–28.51) kg/m² were eligible for the study. The median (IQR) habitual duration of sleep was 6 (6–7) h/night. In all, 283 participants (52%) had a short daytime nap. In 214 (39.3%) participants the Pittsburgh Sleep Quality Index score was >5, with a higher percentage in women (74·3%, p < 0.05). Antibody levels were associated with age (r = −0.178, p < 0.001), poor sleep quality (r = −0.094, p < 0.05), insomnia (r = −0.098, p < 0.05), and nap frequency per week (r = −0.098, p < 0.05), but after adjusting for confounders, only insomnia, gender, and age were independent determinants of antibody levels. It is important to emphasise that insomnia is associated with lower antibody levels against COVID-19 after vaccination.     

Tailoring Titanium Sheet Metal Using Laser Metal Deposition to Improve Room Temperature Single-Point Incremental Forming

Typically, due to their limited formability, elevated temperatures are required in order to achieve complex shapes in titanium alloys. However, there are opportunities for forming such alloys at room temperature using incremental forming processes such as single-point incremental forming (SPIF). SPIF is an innovative metal forming technology which uses a single tool to form sheet parts in place of dedicated dies. SPIFs ability to increase the forming limits of difficult-to-form materials offers an alternative to high temperature processing of titanium. However, sheet thinning during SPIF may encourage the early onset of fracture, compromising in-service performance. An additive step prior to SPIF has been examined to tailor the initial sheet thickness to achieve a homogeneous thickness distribution in the final part. In the present research, laser metal deposition (LMD) was used to locally thicken a commercially pure titanium grade 2 (CP-Ti50A) sheet. Tensile testing was used to examine the mechanical behaviour of the tailored material. In addition, in-situ digital image correlation was used to measure the strain distribution across the surface of the tailored material. The work found that following deposition, isotropic mechanical properties were obtained within the sheet plane in contrast to the anisotropic properties of the as-received material and build height appeared to have little influence on strength. Microstructural analysis showed a change to the material in response to the LMD added thickness, with a heat affected zone (HAZ) at the interface between the added LMD layer and non-transformed substrate material. Grain growth and intragranular misorientation in the added LMD material was observed. SPIF of a LMD tailored preform resulted in improved thickness homogeneity across the formed part, with the downside of early fracture in a high wall angle section of the sheet.     

Chronic biopsy proven post‐COVID myoendocarditis with SARS‐Cov‐2 persistence and high level of antiheart antibodies

PurposeTo study the clinical signs and mechanisms (viral and autoimmune) of myoendocarditis in the long‐term period after COronaVIrus Disease 2019 (COVID‐19).MethodsFourteen patients (nine male, 50.1 ± 10.2 y.o.) with biopsy proven post‐COVID myocarditis were observed. The diagnosis of COVID‐19 was confirmed by IgG seroconversion. The average time of admission after COVID‐19 was 5.5 [2; 10] months. An endomyocardial biopsy (EMB) of the right ventricle was obtained. The biopsy analysis included polymerase chain reaction diagnosis of viral infection, morphological, immunohistochemical (IHC) examination with antibodies to CD3, CD45, CD68, CD20, SARS‐Cov‐2 spike, and nucleocapsid antigens. Coronary atherosclerosis was ruled out in all patients over 40 years.ResultsThe new cardiac symptoms (congestive heart failure 3–4 New York Heart Association class with severe right ventricular involvement, various rhythm, and conduction disturbances) appeared 1–5 months following COVID‐19. Magnetic resonance imaging showed disseminated or focal subepicardial and intramyocardial late gadolinium enhancement, hyperemia, edema, and increased myocardial native T1 relaxation time. Antiheart antibodies levels were increased 3–4 times in 92.9% of patients. The mean left ventricular (LV) ejection fraction (EF) was 28% (24.5; 37.8). Active lymphocytic myocarditis was diagnosed in 12 patients, eosinophilic myocarditis in two patients. SARS‐Cov‐2 RNA was detected in 12 cases (85.7%), in association with parvovirus B19 DNA—in one. Three patients had also endocarditis (infective and nonbacterial, with parietal thrombosis). As a result of steroid and chronic heart failure therapy, the EF increased to 47% (37.5; 52.5).ConclusionsCOVID‐19 can lead to long‐term severe post‐COVID myoendocarditis, that is characterized by prolonged persistence of coronavirus in cardiomyocytes, endothelium, and macrophages (up to 18 months) in combination with high immune activity. Corticosteroids and anticoagulants should be considered as a treatment option of post‐COVID myoendocarditis.     

Peripheral levels of matrix metalloproteinase-9, interleukin-6, and C-reactive protein are elevated in patients with acute coronary syndromes: correlations with serum troponin I

BACKGROUND: Acute coronary syndromes (ACS) are characterized by activation of systemic and local inflammatory mediators. The interrelation between these soluble inflammatory markers and their association with markers of myocardial necrosis have not been extensively studied. HYPOTHESIS: The study was undertaken to evaluate the association of the systemic levels of matrix metalloproteinase-9 (MMP-9) and the tissue inhibitor of metalloproteinase-1 (TIMP-1), with C-reactive protein (CRP), interleukin-6 (IL-6), and serum troponin-I in patients admitted with ACS. METHODS: Analysis of serum concentrations of the above inflammatory markers was performed in 53 patients with unstable angina (UA) and in 15 with non-ST-segment elevation myocardial infarction (NSTEMI) within 48 h of admission, and 34 patients with stable coronary artery disease. RESULTS: Compared with patients with stable angina, those with ACS had elevated admission levels of MMP-9 (p = 0.04), CRP (p < 0.001), and IL-6 (p = 0.001), but not TIMP-1 (p = 0.55). Compared with patients with UA, those with NSTEMI also had higher levels of IL-6 (p < 0.001), CRP (p = 0.002), and MMP-9 (p = 0.05). CONCLUSIONS: In patients with ACS, the admission levels of inflammatory mediators, including MMP-9, CRP, and IL-6 are significantly elevated, specifically in association with serum troponin I. Systemic and local markers of inflammatory activity may be directly associated with myocardial injury.