A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis.

There has been a growing interest in the use of bioabsorbable polymers in interference screws for knee ligament reconstruction surgeries. This interest is driven by virtue of the relevant properties exhibited by these polymers. Among such essential properties include excellent biocompatibility and bioabsorption, good integration between graft/bone, in addition to the ease they offer when it comes to surgical revision. This article seeks to report the results obtained from the study aimed at the development of a bioabsorbable interference screw produced by the injection molding process with two distinct polymeric materials: PLDL poly(L,DL-Lactic acid) and a composite PLDL + 30 wt% TCP (β-tricalcium phosphate). Finite element analysis (FEA) was used for the development of the screw design. The mechanical strength of the screws was evaluated, where the maximum torque to break was found to surpass the insertion torque by 136% in PLDL material and by 190% in PLDL+TCP. The mean values of pullout force obtained for PLDL and PLDL+TCP were 1635 N and 809 N, respectively. An in vitro degradation test performed over a period of 180 days helped to assess the mechanical behavior during degradation and facilitated the comparison of the screws based on specific application requirements. The composite material (PLDL +TCP) exhibited a faster degradation process, with 88% loss of mechanical resistance following 180 days of degradation compared with 55% observed in the PLDL material. The results show that the addition of bioactive ceramic TCP contributed toward raising the initial mechanical resistance and acceleration during the process of degradation.

In this study, different methods of cutting fluid application are used in turning of a difficult-to-machine steel (SAE EV-8). Initially, a semisynthetic cutting fluid was applied using a conventional method (i.e. overhead flood cooling), minimum quantity of cutting fluid, and pulverization. A lubricant of vegetable oil (minimum quantity of lubricant) was also applied using the minimum quantity method. Thereafter, a cutting fluid jet under high pressure (3.0 MPa) was singly applied in the following regions: chip–tool interface, top surface of the chip (between workpiece and chip) and tool–workpiece contact. Moreover, two other methods were used: an interflow between conventional application and chip–tool interface jet (combined method) and, finally, three jets simultaneously applied. In order to carry out these tests, it was necessary to set up a high-pressure system using a piston pump for generating a cutting fluid jet, a venturi for fluid application (minimum quantity of cutting fluid and minimum quantity of lubricant) and a nozzle for cutting fluid pulverization. The output variables analyzed included tool life, surface roughness, cutting tool temperature, cutting force, chip form, chip compression rate and machined specimen microstructure. Among the results, it can be observed that the tool life increases and the cutting force decreases with the application of cutting fluid jet, mainly when it is directed to the chip–tool interface. Excluding the methods involving jet fluid, the conventional method seems to be more efficient than other methods of low pressure, such as minimum quantity of volume and pulverization, when considering just the cutting tool wear.