Graphene Oxide Significantly Modifies Cardiac Parameters and Coronary Endothelial Reactivity in Healthy and Hypertensive Rat Hearts Ex Vivo.

Interactions of graphene oxide (GO) with an ex vivo rat heart and its coronary vessels have not been studied yet. Moreover, the conflicting data on the "structure-properties" relationships do not allow for biomedical applications of GO. Herein, we study the impact of GO on the ex vivo isolated rat heart, normotensive and hypertensive, under the working heart and the constant-pressure perfusion (Langendorff) regimes. Four structural GO variants of the following initial morphology were used: few-layer (below 10-layer) GO1, O < 49%; predominantly single-layer GO2, O = 41-50%; 15-20-layer GO3, O < 11%; and few-layer (below 10-layer) NH4 +-functionalized GO4, O < 44%, N = 3-6%. The aqueous GO dispersions, sonicated and stabilized with bovine serum albumin in Krebs-Henseleit-like solution-uniformized in terms of the particle size-were eventually size-monodisperse as revealed by dynamic light scattering. To study the cardiotoxicity mechanisms of GO, histopathology, Raman spectroscopy, analysis of cardiac parameters (coronary and aortic flows, heart rate, aortic pressure), and nitric oxide (NO-)-dependent coronary flow response to bradykinin (blood-vessel-vasodilator) were used. GO1 (10 mg/L) exerted no effects on cardiac function and preserved an increase in coronary flow in response to bradykinin. GO2 (10 mg/L) reduced coronary flow, aortic pressure in normotensive hearts, and coronary flow in hypertensive hearts, and intensified the response to bradykinin in normal hearts. GO3 (10 mg/L) reduced all parameters in hypertensive hearts and coronary response to bradykinin in normal hearts. At higher concentrations (normotensive hearts, 30 mg/L), the coronary response to bradykinin was blocked. GO4 (10 mg/L) reduced the coronary flow in normal hearts, while for hypertensive hearts, all parameters, except the coronary flow, were reduced and the coronary response to bradykinin was blocked. The results showed that a low number of GO layers and high O-content were safer for normal and hypertensive rat hearts. Hypertensive hearts deteriorated easier upon perfusion with low-O-content GOs. Our findings support the necessity of strict control over the GO structure during organ perfusion and indicate the urgent need for personalized medicine in biomedical applications of GO.

Recycled aluminium feedstock in metal additive manufacturing: A state of the art review.

Additive manufacturing has revolutionised the production of functional components and assemblies, offering a high degree of manufacturing flexibility. This review explores the latest advancements in additive manufacturing, focusing on its fusion-based and solid-state based technologies, and highlights the use of recycled aluminium as feedstock in these processes. The advantages and limitations of incorporating recycled materials are thoroughly analysed, considering factors such as material properties, sustainability, and process acceptance. While up to 14.4 kg CO2 per kg of aluminium is released during primary aluminium ingot production, solid-state based additive manufacturing, which is tolerant of feedstock contamination, can directly recycle aluminium. Meanwhile, fusion based additive manufacturing can readily utilise recycling pathways such as maintaining grade, upcycling, and downcycling, as well as powder reuse, providing opportunities for significant emissions reduction. The examination of feedstock manufacturing in this review, such as wire for WAAM and powder for PBF, indicates that this step indirectly increases the resource consumption of additive manufacturing. Finally, the alignment of aluminium recycling and additive manufacturing with Circular Economy principles and the UN's sustainable development goals are addressed, highlighting contributions to SDGs 3, 9, and 12.

Stabilization of Graphene Oxide Dispersion in Plasma-like Isotonic Solution Containing Aggregating Concentrations of Bivalent Cations.

Graphene oxide's (GO) intravascular applications and biocompatibility are not fully explored yet, although it has been proposed as an anticancer drug transporter, antibacterial factor or component of wearable devices. Bivalent cations and the number of particles' atom layers, as well as their structural oxygen content and pH of the dispersion, all affect the GO size, shape, dispersibility and biological effects. Bovine serum albumin (BSA), an important blood plasma protein, is expected to improve GO dispersion stability in physiological concentrations of the precipitating calcium and magnesium cations to enable effective and safe tissue perfusion. METHODS: Four types of GO commercially available aqueous dispersions (with different particle structures) were diluted, sonicated and studied in the presence of BSA and physiological cation concentrations. Nanoparticle populations sizes, electrical conductivity, zeta potential (Zetasizer NanoZS), structure (TEM and CryoTEM), functional groups content (micro titration) and dispersion pH were analyzed in consecutive preparation stages. RESULTS: BSA effectively prevented the aggregation of GO in precipitating concentrations of physiological bivalent cations. The final polydispersity indexes were reduced from 0.66-0.91 to 0.36-0.43. The GO-containing isotonic dispersions were stable with the following Z-ave results: GO1 421.1 nm, GO2 382.6 nm, GO3 440.2 nm and GO4 490.1 nm. The GO behavior was structure-dependent. CONCLUSION: BSA effectively stabilized four types of GO dispersions in an isotonic dispersion containing aggregating bivalent physiological cations.

Application of a New Alloy and Post Processing Procedures for Laser Cladding Repairs on Hypereutectoid Rail Components.

The development of a laser cladding repair strategy is critical for the continued growth of heavy-haul railway networks. Premium hypereutectoid rails have undergone laser cladding using a new martensitic stainless-steel alloy, 415SS, developed for high carbon rails after standard cladding metals were found to be incompatible. Non-destructive neutron diffraction techniques were used to measure the residual stress in different layers generated across a dissimilar metal joint during laser cladding. The internal stress distribution across the cladding, heat-affected zone (HAZ), and substrate was measured in the untempered rail, after 350 °C and 540 °C heat treatment procedures and two surface grinding operations. The martensitic 415SS depositions produce compressive stress in the cladding, regardless of tempering procedures, which may inhibit fatigue crack propagation whilst grinding operations locally relive surface stress. Balancing tensile stresses were recorded below the fusion boundary in the HAZ due to thermal gradients altering the microstructure. The combination of 540 °C tempering and 0.5 mm surface layer removal produced a desirable combination of compression in the cladding deposition with significantly reduced tensile stresses in the HAZ. A comparison with the current literature shows that this alloy achieves a unique combination of desirable hardness, low tensile stress, and compression in the cladding layer. Data obtained during strain scanning has been used to determine the location of microstructural changes at the fusion boundary and HAZ through correlation of the stress, strain, full width at half maximum (FWHM), and intensity profiles. Therefore, neutron diffraction can be used for both the accurate measurement of internal residual stress and to obtain microstructural information of a metallurgical join non-destructively.

Residual Stress Measurement Techniques for Metal Joints, Metallic Coatings and Components in the Railway Industry: A Review.

Manufacturing and maintenance procedures in the railway industry regularly implement welding and metal deposition operations to produce joints, coatings and repair structures. During these processes, residual stresses arise through the generation of heat affected zones and plastic deformation. This makes accurate measurements of the internal stresses a critical aspect of manufacturing, monitoring, repair and model validation in the develop new metallic coating and joining technologies. Selection of an appropriate residual stress measurement method has many important factors including component size, resolution and the magnitude and location of internal stresses, often resulting in a combination of techniques required to obtain complete assessment of the stress state. This paper offers a review of residual stress measurement techniques for railway components including rail joints and coatings through comparison of destructive and non-destructive approaches, their measurement capabilities, benefits and limitations. A comprehensive discussion of different applications is provided with a summary of facilities available to both research and industry.

Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds.

High Strength Low Alloy (HSLA) steels are the materials of choice in pipeline construction with the API X70 grade as the steel for the majority of pipeline networks constructed during the late 20th and early this century. This paper reports on the influence of Post-Weld Heat Treatment (PWHT) on the reduction of residual stresses, resulting changes in the microstructure, and mechanical properties of a multi-pass, X70 HSLA steel, weld joints made by a combined Modified Short Arc Welding (MSAW) and Flux Cored Arc Welding (FCAW) processes. Neutron diffraction results highlighted high magnitude of tensile residual stresses, in excess of yield strength of both parent and weld metal, in the as-welded specimen (~650 MPa), which were decreased substantially as a result of applying PWHT (~144 MPa). Detailed microstructural studies are reported to confirm the phase transformation during PWHT and its interrelationship with mechanical properties. Transmission Electron Microscopy (TEM) analysis showed polygonization and formation of sub-grains in the PWHT specimen which justifies the reduction of residual stress in the heat-treated weld joints. Furthermore, microstructural changes due to PWHT justify the improvement in ductility (increase in the elongations) with a slight reduction in yield and tensile strength for the PWHT weld joint.

Critical deposition height for sustainable restoration via laser additive manufacturing.

Laser material deposition based restoration of high-value components can be a revolutionary technology in remanufacturing. The deposition process induces residual stresses due to thermomechanical behavior and metallurgical transformations. The presence of tensile residual stresses in the deposited layer will compromise the fatigue life of the restored component. We have developed a novel fully coupled metallurgical, thermal and mechanical (metallo-thermomechanical) model to predict residual stresses and identified a critical deposition height, which ensures compressive residual stresses in the deposited layer. Any lower deposition height will result in tensile residual stresses and higher deposition height will result in excessive dilution (substrate melting). We have validated the model using neutron and micro-focus X-ray diffraction measurements. This study highlights that the critical deposition height corresponds to the minimum cooling rate during solidification. It addresses one of the major outstanding problems of additive manufacturing and paves a way for "science-enabled-technology" solutions for sustainable restoration/remanufacturing.

Analysis of Therapeutic Effectiveness of Selected Types of Collagen in Prevention and Treatment of Degenerative Joint Disease.

Loss of collagen is a natural development accompanying aging of the body. It may be additionally accelerated by various conditions, including osteoarthritis (OA). Within the last two decades numerous and diverse studies have been conducted worldwide with the aim of identifying substances containing collagen, producing therapeutic preparations of expected effectiveness in the prevention and therapy of OA that would be safe to use and developing methods of delivering the final product into the body. The authors reviewed and analysed the latest available literature by selecting papers presenting the findings of studies conducted in line with the principles of Evidence-Based Medicine (EBM). The studies have been ordered from in vitro trials (studies on animals in the laboratory setting, use of tissue engineering methods to assess the effect of cartilage transplants, use of different collagen types for development of scaffolds etc.) to in vivo clinical trials. It appears that the findings of the latest multidimensional studies presented below, which confirm the therapeutic effectiveness of new-generation injectable medical collagen preparations, will help these medical products gain their well-deserved position in the comprehensive treatment of osteoarthritis both with respect to their analgesic properties as well as their ability to enable functional recovery and stimulate regeneration of tissues at the molecular level.

Assessment of the relationship between selected cardiovascular risk factors and the indices of intima-media thickness and coronary artery calcium score in various stages of chronic kidney disease.

Renal diseases pose a growing epidemiological and health problem worldwide. Cardiovascular diseases are the leading cause of deaths among patients with chronic kidney disease. Increased risk of atherosclerosis in these patients results from the occurrence of traditional and non-traditional risk factors. The aim of this study was to assess the relationship between selected risk factors for cardiovascular diseases (age, sex, dyslipidemia, hypertension, etc.), intima-media thickness and coronary artery calcium score in patients with chronic kidney disease stages 2, 3 and 4. This study included 60 patients with chronic kidney disease divided into 3 groups on the basis of disease stage and control group consisting of 20 individuals without diagnosed chronic kidney disease and cardiovascular diseases. Blood analysis and blood pressure measurements were taken. All patients underwent carotid artery ultrasound with the assessment of the intima-media thickness, and heart CT scan in order to assess the index of coronary artery calcification. Logistic regression analysis revealed statistically significant correlation between blood vessels calcification and age--the increase in age by 1 year was associated with the increase in the risk of coronary artery calcification by 6.7 %. The increase in IMT by about 0.1 mm raises the risk of calcification by about 2 %. Second logistic regression model revealed that one-year increase in age was associated with an increase in the risk of intima-media thickening by 6.5 %. Occurrence of hypertension was associated with a ninefold increase in intima-media thickening risk in comparison with patients with normal blood pressure. To sum up, age and hypertension were associated with the growth of IMT in CKD patients, while age and exposure to tobacco smoke were associated with the increase in coronary artery calcium score. The relationship between thickening of IMT and the increase in calcification index in patients was also observed in study group.

The risk of atherosclerosis in patients with chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is becoming a serious health problem; the number of people with impaired renal function is rapidly rising, especially in industrialized countries. A major complication of CKD is cardiovascular disease. Accelerated atherosclerosis has been observed in early stages of renal dysfunction. The purpose of this study was to examine the relationship between the degree of renal insufficiency and both the prevalence and intensity of coronary artery disease (assessed on the basis of number of vessels with stenosis). METHODS: 446 individuals with both serum creatinine >120 µmol/l (men) or >96 µmol/l (women) and acute coronary syndrome were included in the study. All patients included in this analysis underwent urgent coronarography. Data concerning glomerular filtration rate (GFR), number of vessels with stenosis, hypertension, lipid disorders, creatinine concentration, C-reactive protein, glucose and lipid profile were analyzed. RESULTS: This study confirmed that moderate to severe renal impairment is associated with accelerated atherosclerosis. Moreover, patients with GFR values below 60 ml/min/1.73 m(2) are predisposed to accelerated, multivessel cardiovascular disease. CONCLUSIONS: GFR seems to be an independent risk factor for multivessel cardiovascular disease. Due to the fact that patients with renal dysfunction are at high risk of cardiovascular events, they should obtain optimal treatment resulting not only in kidney protection but also in the elimination of cardiovascular risk factors.

Massage therapy in myofascial TMD pain management.

Myofascial pain located in the area of the head is a very common disease of the stomatognathic system. The fact that the mechanism of its development is very complex may cause a variety of problems in diagnosis and therapy. Patients diagnosed with this type of affliction usually need a variety of different therapies. Massage therapy can be a significant method of treatment of myofascial pain. That kind of therapy is clinically useful as it improves the subjective and objective health status of the patient and is easy to follow. The aim of this paper is to show the physiological effect and different massage techniques applied in myofascial pain treatment. The authors would also like to present the protocol for dealing with patients who demand that kind of therapy for masseter and temporal muscles.