Inkjet system for printing mechanical reinforcing patterns directly on fragile membranes floating on liquid surfaces

Ultrathin porous membranes can be employed for applications in the field of micro- and ultrafiltration and offer a low flow resistance. However, due to their thickness below 1 m they are very fragile. Therefore, we recently reported on a process to increase the mechanical stability by inkjet printing of UV curable inks to create reinforcing patterns on top of these membranes [1]. Based on this laboratory approach we realized now a specific inkjet printing system to apply the process efficiently on larger areas. The membranes are first manufactured on a water surface in a Langmuir trough [2]. Therefore, the inkjet system realized here is composed of a 3D motion system for a multi-nozzle printhead and a UVLED-lamp. In order to prevent waves leading to undefined displacements of the floating membranes the filled trough is stationary while the printhead and the UVLED-lamp are moved. The positioning stages have a high accuracy and enable a precise movement of the printing an d UV curing device relative to the membranes. Deviating from previous procedures that needed intermittent support of the porous membrane by a solid support, the reinforcing patterns now are created directly on top of the floating membranes. Deposition is done by multiple motion procedures combined with triggered printing and UV curing events. The patterns can be deposited in several minutes with resolutions of up to 800 dpi covering an area of about 130 cm2. While the porous membranes before application of reinforcement pattern are very fragile, the reinforced porous membranes are stable enough to be lifted off the water surface and handled manually without special precautions. ©2012 Society for Imaging Science and Technology

Circadian variations of blood pressure and heart rate early and late after heart transplantation

Cardiac reinnervation late after heart transplantation has been reported in individual patients. As a measure for reinnervation, circadian changes in arterial blood pressure and heart rate have been used but not yet systemically evaluated in cardiac transplant recipients. Ambulatory blood pressure and heart rate monitoring was performed in 62 patients for 24 hr early (<6 months, mean 26 days, range 5-90 days, n=30) and late (> or = 6 months, mean 12 months, range 7-78 months, n=32) after heart transplantation. A loss of physiological nocturnal decline in blood pressure and heart rate was noted early after transplantation, whereas late after operation an improvement in circadian changes of blood pressure and heart rate was observed. The patients late after heart transplantation had a significant higher diastolic blood pressure. A pathological circadian blood pressure and heart rate pattern was observed in patients early after heart transplantation, which was improved late after operation. This could be explained by partial reinnervation of the heart. Diastolic hypertension late after transplantation may be due to cyclosporine treatment and/or neuroendocrine hyperactivity

Printing Reinforcing Structures onto Microsieves that are Floating on a Water Surface

This article describes the preparation of hierarchically structured microsieves via a suitable combination of float-casting and inkjet-printing: A mixture of hydrophobized silica particles of 600 nm +/- 20 nm diameter, a suitable nonwater-soluble nonvolatile acrylic monomer, a nonvolatile photoinitiator, and volatile organic solvents is applied to a water surface. This mixture spontaneously spreads on the water surface; the volatile solvents evaporate and leave behind a layer of the monomer/initiator mixture comprising a monolayer of particles, each particle protruding out of the monomer layer at the top and bottom surface. Photopolymerization of the monomer converts this mixed layer into a solid composite membrane floating on the water surface. Onto this membrane, while still floating on the water surface, a hierarchical reinforcing structure based on a photocurable ink is inkjet-printed and solidified. In contrast to the nonreinforced membrane, the reinforced membrane can easily be lifted off the water surface without suffering damage. Subsequently, the silica particles are removed, and thus, the reinforced composite membrane is converted into a reinforced microsieve of 350 nm +/- 50 nm thickness bearing uniform through pores of 465 nm +/- 50 nm diameter. This reinforced microsieve is mounted into a filtration unit and used to filter model dispersions: its permeance for water at low Reynolds numbers is in accordance with established theories on the permeance of microsieves and significantly above the permeance of conventional filtration media; it retains particles exceeding the pore size, while letting particles smaller than the pore size pass

Inkjet Printing of Self‐Supporting and Self‐Contained Structured Objects Onto Liquid Surfaces

Some applications in miniaturized fabrication like valves or force sensors require self‐supporting structures. These may be generated on top of a solid substrate and separated from it afterwards, but this separation is an additional manufacturing step and may stress the structure. Therefore, it may be of advantage to create the desired objects directly on top of a liquid. Here, it is shown that self‐supporting and self‐contained structures including lines of defined width, full tone squares and delicate structures with non‐uniform line width, edges and openings can be prepared by inkjet printing of a photo‐curable ink onto a water surface followed by irradiation with ultraviolet light and lift‐off. To make this feasible, convection, spreading, and dewetting of the ink from the water surface has to be suppressed by controlling the timing of the irradiation, the mobility of the water surface and the long and short range interactions between the printed ink and the water substrate. These tasks may be achieved via addition of soluble amphiphiles or via spreading of water insoluble amphiphiles or hydrophobized particles onto the water surface prior to printing. Best results are obtained by printing the desired structures onto a water surface that bears a monolayer of hydrophobized particles

The failing human heart is unable to use the frank- starling mechanism

There is evidence that the failing human left ventricle in vivo subjected to additional preload is unable to use the Frank-Starling mechanism. The present study compared the force-tension relation in human nonfailing and terminally failing (heart transplants required because of dilated cardiomyopathy) myocardium. Isometric force of contraction of electrically driven left ventricular papillary muscle strips was studied under various preload conditions (2 to 20 mN). To investigate the influence of inotropic stimulation, the force-tension relation was studied in the presence of the cardiac glycoside ouabain. In skinned-fiber preparations of the left ventricle, developed tension was measured after stretching the preparations to 150% of the resting length. To evaluate the length-dependent activation of cardiac myofibrils by Ca2+ in failing and nonfailing myocardium, the tension-Ca2+ relations were also measured. After an increase of preload, the force of contraction gradually increased in nonfailing myocardium but was unchanged in failing myocardium. There were no differences in resting tension, muscle length, or cross-sectional area of the muscles between both groups. Pretreatment with ouabain (0.02 mumol/L) restored the force-tension relation in failing myocardium and preserved the force-tension relation in nonfailing tissue. In skinned-fiber preparations of the same hearts, developed tension increased significantly after stretching only in preparations from nonfailing but not from failing myocardium. The Ca2+ sensitivity of skinned fibers was significantly higher in failing myocardium (EC50, 1.0; 95% confidence limit, 0.88 to 1.21 mumol/L) compared with nonfailing myocardium (EC50, 1.7; 95% confidence limit, 1.55 to 1.86 mumol/L). After increasing the fiber length by stretching, a significant increase in the sensitivity of the myofibrils to Ca2+ was observed in nonfailing but not in failing myocardium. These experiments provide evidence for an impaired force-tension relation in failing human myocardium. On the subcellular level, this phenomenon might be explained by a failure of the myofibrils to increase the Ca2+ sensitivity after an increase of the sarcomere length

Roll-to-roll infrared sintering of gravure printed silver patterns in applications of back-injection-molded functional lightweight structures

We report on the manufacturing of functional lightweight structures by the combination of roll-to-roll gravure printing technology and back injection molding technology. The objective is to manufacture conductive grid patterns consisting of thin lines in the lower micrometer range integrated in lightweight components. We already reported on the roll-to-roll manufacture of thin conductive lines by gravure printing of a nano-silver ink which is rapidly sintered by infrared radiation at web velocities up to 1 m/s [1][2]. This approach is employed for the fast manufacturing of conductive grid patterns on a flexible substrate. Afterwards, the printed patterns are integrated in lightweight structures by back injection molding. The final composites shall be applied as smart components for example in cars and rotor blades of wind turbines for electrical applications like power supply, electrical circuits and data communication [3]

Aspirin and mortality from coronary bypass surgery

BACKGROUND: There is no therapy known to reduce the risk of complications or death after coronary bypass surgery. Because platelet activation constitutes a pivotal mechanism for injury in patients with atherosclerosis, we assessed whether early treatment with aspirin could improve survival after coronary bypass surgery. METHODS: At 70 centers in 17 countries, we prospectively studied 5065 patients undergoing coronary bypass surgery, of whom 5022 survived the first 48 hours after surgery. We gathered data on 7500 variables per patient and adjudicated outcomes centrally. The primary focus was to discern the relation between early aspirin use and fatal and nonfatal outcomes. RESULTS: During hospitalization, 164 patients died (3.2 percent), and 812 others (16.0 percent) had nonfatal cardiac, cerebral, renal, or gastrointestinal ischemic complications. Among patients who received aspirin (up to 650 mg) within 48 hours after revascularization, subsequent mortality was 1.3 percent (40 of 2999 patients), as compared with 4.0 percent among those who did not receive aspirin during this period (81 of 2023, P<0.001). Aspirin therapy was associated with a 48 percent reduction in the incidence of myocardial infarction (2.8 percent vs. 5.4 percent, P<0.001), a 50 percent reduction in the incidence of stroke (1.3 percent vs. 2.6 percent, P=0.01), a 74 percent reduction in the incidence of renal failure (0.9 percent vs. 3.4 percent, P<0.001), and a 62 percent reduction in the incidence of bowel infarction (0.3 percent vs. 0.8 percent, P=0.01). Multivariate analysis showed that no other factor or medication was independently associated with reduced rates of these outcomes and that the risk of hemorrhage, gastritis, infection, or impaired wound healing was not increased with aspirin use (odds ratio for these adverse events, 0.63; 95 percent confidence interval, 0.54 to 0.74). CONCLUSIONS: Early use of aspirin after coronary bypass surgery is safe and is associated with a reduced risk of death and ischemic complications involving the heart, brain, kidneys, and gastrointestinal tract