Quaternary Zinc Alloys with Magnesium, Calcium and Strontium after Hydrostatic Extrusion-Microstructure and Its Impact on Mechanical and Corrosion Properties.

The development of bioabsorbable implants from Zn alloys is one of the main interests in the new generation of biomaterials. The main drawbacks of Zn-based materials are their insufficient mechanical properties. In the presented studies, a quaternary alloy composed of zinc with magnesium (0.

Thermo-Mechanical Treatment for Reducing the Wear Rate of CuCrZr Tool Electrodes during Electro-Discharge Machining.

The research presented in this paper focused on optimising the process of unconventional plastic forming by hydrostatic extrusion (HE) with post-processing heat treatment of a copper alloy (CuCrZr) for electro-discharge machining (EDM) applications. The treatment was carried out in such a way as to obtain a material with an improved microstructure, characterised by a significant increase in hardness and strength while maintaining a high electrical conductivity, thus achieving the main goal of reducing electrode wear in the EDM process. As part of the research, a material with an ultrafine-grained structure was obtained with an average grain size of = 320 nm and a much higher strength of = 645 MPa compared to the material in the initial state ( = 413 MPa).

Effect of microstructure refinement of pure copper on improving the performance of electrodes in electro discharge machining (EDM).

The paper presents an analysis of the impact of plastic deformation using hydrostatic extrusion (HE) on the structural, mechanical and functional properties of pure copper for use as electrodes in the process of electro discharge machining (EDM). As part of the research, copper was subjected to the HE process with the maximum cumulative true strain equal to ɛ = 3.89 obtained in 5 stages.

In-situ experimental study on hydro-borehole technology application to improve the hard coal excavating techniques in coal mine.

The hydro-mining technology is considered as a promising method of bituminous coal excavation. The paper presents the results of the in-situ experimental campaign and modelling of hydro-cutting technology application. The proposed innovative technology was tested in terms of the effects of the distance between the outlet of water from the nozzle and a sidewall, pressure of the water jet, as well as the type of a nozzle on hydro-mining effectiveness.

The impact of severe plastic deformations obtained by hydrostatic extrusion on the machinability of ultrafine-grained Ti grade 2 intended for fasteners.

The study aimed to examine the effect of the hydrostatic extrusion (HE) process on the machinability of Ti grade 2 (Ti) in the turning process. After the deformation with true strain ɛ = 2.28, the microstructure was significantly refined to a grain size of 100 nm, resulting in an increase in the mechanical properties, UTS strength by 190%, YS yield strength by 230%Cutting forces for Ti in the initial state and after HE were analyzed at cutting depths a = 0.

Influence of Strain Rates during Severe Plastic Strain Processes on Microstructural and Mechanical Evolution in Pure Zinc.

The study presents an analysis of the influence of the plastic strain rate on the mechanical and structural properties of pure zinc. Thanks to the use of unconventional methods of plastic processing, the process of the equal channel angular pressing (ECAP) and the process of hydrostatic extrusion (HE), the tests were performed in a wide range of plastic strain rates, between 0.04 s and 170 s.

Mechanical Reinforcement of Polyamide 6 by Cold Hydrostatic Extrusion.

This paper presents the effect of severe plastic deformation obtained using the cold hydrostatic extrusion (HE) method on the mechanical and structural properties of polyamide 6 (PA6). As a result of the plastic strain, a significant increase in ultimate tensile strength and tensile modulus were observed. Tensile strength rose by almost 500%, up to the level of 508 MPa, whereas the tensile modulus rose by about 65%.

Microstructural Investigation of a Friction-Welded 316L Stainless Steel with Ultrafine-Grained Structure Obtained by Hydrostatic Extrusion.

The paper presents the microstructural investigation of a friction-welded joint made of 316L stainless steel with an ultrafine-grained structure obtained by hydrostatic extrusion (HE). Such a plastically deformed material is characterized by a metastable state of energy equilibrium, increasing, among others, its sensitivity to high temperatures. This feature makes it difficult to weld ultra-fine-grained metals without losing their high mechanical properties.

On-Pump vs Off-Pump coronary artery bypass surgery in atrial fibrillation. Analysis from the polish national registry of cardiac surgery procedures (KROK).

Background: No single randomized study has ever before addressed the safety of On-Pump coronary artery bypass grafting (CABG) vs Off-Pump CABG in the setting of atrial fibrillation (AF) and data from small observational samples remain inconclusive.

Methods And Findings: Procedural data from KROK (Polish National Registry of Cardiac Surgery Procedures) were retrospectively collected. Of initial 188,972 patients undergoing CABG, 7,913 presented with baseline AF (76.

Surgical ablation for atrial fibrillation during isolated coronary artery bypass surgery.

Objectives: Our goal was to evaluate early sequelae and long-term survival in patients undergoing isolated coronary artery bypass grafting (CABG) with concomitant surgical ablation for atrial fibrillation (AF).

Methods: Procedural data from KROK (Polish National Registry of Cardiac Surgery Procedures) were collected. A total of 7879 patients with underlying AF underwent isolated CABG between 2006 and 2018 in 37 reference centres across Poland.

Survival after surgical ablation for atrial fibrillation in mitral valve surgery: Analysis from the Polish National Registry of Cardiac Surgery Procedures (KROK).

Objectives: Surgical ablation for atrial fibrillation (AF) performed at the time of other valvular- or nonvalvular cardiac procedure is a mainstay of therapy; yet the data regarding its influence on remote survival are sparse. We aimed to evaluate late survival in patients undergoing mitral valve (MV) surgery with concomitant surgical ablation for AF.

Methods: Procedure-related data from the Polish National Registry of Cardiac Surgery Procedures (Krajowy Rejestr Operacji Kardiochirurgicznych) were retrospectively collected.

Expression of sex steroid receptors and aromatase in adipose tissue in different body regions in men with coronary artery disease with and without ischemic systolic heart failure.

The hormonal metabolism of adipose tissue differs across regions of fat. This issue has never been verified in male patients with coronary artery disease (CAD) with and without systolic heart failure (SHF). We examined 90 male patients with CAD with and without SHF and 42 healthy controls.

Giant saccular superior vena cava aneurysm-a rare and difficult clinical case.

A superior vena cava (SVC) aneurysm is an extremely rare case of vascular malformation in the chest cavity. This is a report of a case of a 57-year-old woman with a saccular SVC aneurysm which was 8 cm wide. The chest computed tomography (CT) scan confirmed a giant 75 mm × 79 mm × 81 mm mass containing the contrast medium from SVC, constricting the right lung parenchyma, narrowing the right innominate vein, in contact with the anterolateral chest cavity wall, and adjoining the superior mediastinum.

Can cardiopulmonary bypass system with blood priming become a new standard in coronary surgery?

Background: Commonly used cardiopulmonary bypass systems with cardiotomy reservoir, oxygenator, and roller pump require preoperative crystalloid filling. Radical reduction of the filling fluid volume and replacing it with the patient's own blood has a fundamental impact on the outcome.

Aim: A comparison of cardiopulmonary bypass filled with the patient's blood, applied in Poland for the first time, and the classical system filled with crystalloids.

Late Cardiac Tamponade as a Result of Parietal Pericardium Erosion.

Late onset cardiac tamponade is a rare and particularly challenging (both from diagnostic and management perspectives) complication of intracardiac lead implantation. We present a case of a late tamponade leading to cardiogenic shock, which occurred 1,164 days after implantable cardioverter-defibrillator (ICD) implantation. Open repair revealed unusual and, to our knowledge, not yet reported mechanism of the disease.

Bone marrow iron depletion is common in patients with coronary artery disease.

Background/objectives: Iron deficiency (ID) may be an important, treatable co-morbidity complicating cardiovascular diseases, but considerable uncertainty exists about the diagnostic accuracy of blood tests. Accordingly, we investigated the relationship between blood tests for ID and iron stores in bone marrow aspirates, the diagnostic gold-standard for ID, in patients with stable coronary artery disease (CAD).

Methods: Bone marrow aspirates were obtained from 65 patients with stable CAD undergoing cardiac surgery and 10 healthy controls.

[Early bioprosthetic mitral valve thrombosis].

We present a case of a 70 year-old woman operated due to severe mitral regurgitation. Early after surgery transthoracic echocardiography revealed the decreased effective orifice area of the implanted bioprosthetic valve and the stenotic features of transvalvular flow. Transesophageal echocardiography (TEE) disclosed a thrombotic cause of heterograft dysfunction.

[Vascular anomaly - left anterior descending artery originating from right coronary sinus].

A case of a patient with congenital anomaly of coronary blood vessels with left anterior descending artery starting from right coronary sinus is presented. The patient was operated on due to symptoms of myocardial ischaemia by carrying out an off-pump coronary artery bypass graft to left anterior descending artery and obtuse marginal artery, with a very good outcome.