Wettability of Metal Surfaces Affected by Paint Layer Covering

The aim of the work was to quantify the surface wettability of metallic (Fe, Al, Cu, brass) surfaces covered with sprayed paints. Wettability was determined using the contact angle hysteresis approach, where dynamic contact angles (advancing Θ_A and receding Θ_R) were identified with the inclined plate method. The equilibrium, Θ_Y, contact angle hysteresis, CAH = Θ_A − Θ_R, film pressure, Π, surface free energy, γ_SV, works of adhesion, W_A, and spreading, W_S, were considered. Hydrophobic water/solid interactions were exhibited for the treated surfaces with the dispersive term contribution to γ_SV equal to (0.66–0.69). The registered 3D surface roughness profiles allowed the surface roughness and surface heterogeneity effect on wettability to be discussed. The clean metallic surfaces turned out to be of a hydrophilic nature (Θ_Y < 90°) with high γ_SV, heterogeneous, and rough with a large CAH. The surface covering demonstrated the parameters’ evolution, Θ_A↑, Θ_R↑, γ_SV↓, W_A↓, and W_S↓, corresponding to the surface hydrophobization and exhibiting base substratum-specific signatures. The dimensionless roughness fluctuation coefficient, η, was linearly correlated to CAH. The CAH methodology based on the three measurable quantities, Θ_A, Θ_R, and liquid surface tension, γ_LV, can be a useful tool in surface-mediated process studies, such as lubrication, liquid coating, and thermoflow.     

Numerical and Experimental Analysis of Titanium Sheet Forming for Medical Instrument Parts

The paper analyses the forming of the surgical instrument handles made of Grade 2 titanium sheets. Sheet metal forming is a technology ensuring high strength and light weight of products. Replacing stainless steels with titanium further reduces instrument weight and additionally provides the required resistance to corrosive environments typical for surgeries. The low instrument weight is important to prevent fatigue of surgeons and allow them to maintain high operational accuracy during long term surgeries. The numerical analysis of the technological process was performed in order to adapt it to forming tool handles using titanium sheets instead of steel sheets. The numerical calculations were experimentally verified. It was found that, in the case of titanium handles, it is necessary to use a blank holder in the first forming operation to eliminate sheet wrinkling in the flange area. The shape and dimensional accuracy of the drawn part after trimming were high enough and the 4th forming operation became unnecessary. Moreover, the process modification included lubrication using rapeseed oil with the addition of boric acid, which effectively prevents the galling of titanium on the working surfaces of the steel tools and ensures a more uniform distribution of plastic strains in the drawn part.     

Evaluation of depression in patients with alzheimer's disease according to the location of medical care

The objective of the study was to assess the severity of depression and to assess the level of self-sufficiency of patients with Alzheimer's disease, with particular emphasis on the place of residence and level of education. The study covered 90 people diagnosed with Alzheimer's disease. All respondents were persons over 65?years of age and residents of cities with a population over one-hundred thousand. The research method based on this work is the author's own questionnaire, the Zung Self-Rating Depression Scale (ZSDS) about depression and the Karnofsky Performance Scale Index (KPSI) for assessment of a patient's self-sufficiency. Regardless of residence, patients with Alzheimer's disease displayed signs of mild or moderate depression (100% in social welfare homes and hospital patients and 60% in those with caregivers at home). Patients with Alzheimer's disease have an unsatisfactory salary in social-economic terms. In those with Alzheimer's disease, quality of life is best for those in family homes under the care of their immediate family. People with a vocational education were the largest group of people diagnosed with Alzheimer's. Patients at home and in the hospital had a higher level of physical activity, but most patients in the hospital needed regular medical care, as did patients in social welfare homes.     

Coordination polymerization of lactides, 3. Copolymerization of L,L-lactide and ε-caprolactone in the presence of initiators containing Zn and Al

High-molecular-weight copolymers of L ,L -lactide with ε-caprolactone were synthesized using initiators containing aluminium and zinc, i.e., AlEt₂OEt, ZnEtOiPr, Al(acac)₃ and AlEt₃ + ZnEt₂ + H₂O. The chain microstructure was revealed to vary from random to diblock arrangement, depending on temperature and the kind of initiator used. In case of Al(acac)₃ as initiator, the reactivity ratios of L ,L -lactide and ε-caprolactone were determined to be r_L = 44 and r_C = 0,28, respectively.     

Biological and Pro-Angiogenic Properties of Genetically Modified Human Primary Myoblasts Overexpressing Placental Growth Factor in In Vitro and In Vivo Studies

Cardiovascular diseases are a growing problem in developing countries; therefore, there is an ongoing intensive search for new approaches to treat these disorders. Currently, cellular therapies are focused on healing the damaged heart by implanting stem cells modified with pro-angiogenic factors. This approach ensures that the introduced cells are capable of fulfilling the complex requirements of the environment, including the replacement of the post-infarction scar with cells that are able to contract and promote the formation of new blood vessels that can supply the ischaemic region with nutrients and oxygen. This study focused on the genetic modification of human skeletal muscle cells (SkMCs). We chose myoblast cells due to their close biological resemblance to cardiomyocytes and the placental growth factor (PlGF) gene due to its pro-angiogenic potential. In our in vitro studies, we transfected SkMCs with the PlGF gene using electroporation, which has previously been proven to be efficient and generate robust overexpression of the PlGF gene and elevate PlGF protein secretion. Moreover, the functionality of the secreted pro-angiogenic proteins was confirmed using an in vitro capillary development assay. We have also examined the influence of PlGF overexpression on VEGF-A and VEGF-B, which are well-known factors described in the literature as the most potent activators of blood vessel formation. We were able to confirm the overexpression of VEGF-A in myoblasts transfected with the PlGF gene. The results obtained in this study were further verified in an animal model. These data were able to confirm the potential therapeutic effects of the applied treatments.