Improvement in workability of terminals placed along the inner side of port vertical breakwaters by means of recurved parapet walls

The function of main port breakwaters is to protect harbour basins from incoming waves and currents. In the event that a maritime terminal is placed on the inner side of a main breakwater, it is extremely important to limit waves overtopping the structure, because the overtopping flows may be very dangerous for the safety of the operations taking place in the terminal. Very often during storms if the overtopping discharges are severe, the terminal is temporarily closed, reducing its average annual workability accordingly. Wave overtopping is normally limited by using high parapet walls (crownwalls) which are not well considered from an environmental point of view due to their visual impact. A good solution to reduce wave overtopping limiting the increasing of the crownwalls height, is to use recurved parapet walls. The paper presents a new formula for recurved walls which can be used to estimate the overtopping flow rates reduction compared to normal vertical parapets. The formula has been obtained for vertical breakwaters by using numerical computations. The recurved parapet has the shape of a circumference sector, characterized by a radius and an opening angle. The numerical computations were performed applying OpenFOAM® which solves the 3D RANS equations for multiphase flows (air and water). The results show the high hydraulic efficiency of recurved walls in reducing overtopping rates compared to traditional vertical parapets

Aircraft interior noise reduction by alternate resonance tuning

Existing interior noise reduction techniques for aircraft fuselages perform reasonably well at higher frequencies, but are inadequate at lower, particularly with respect to the low blade passage harmonics with high forcing levels found in propeller aircraft. A method is being studied which considers aircraft fuselages lines with panels alternately tuned to frequencies above and below the frequency to be attenuated. Adjacent panels would oscillate at equal amplitude, to give equal source strength, but with opposite phase. Provided these adjacent panels are acoustically compact, the resulting cancellation causes the interior acoustic modes to become cut off and therefore be non-propagating and evanescent. This interior noise reduction method, called Alternate Resonance Tuning (ART), is currently being investigated both theoretically and experimentally. This new concept has potential application to reducing interior noise due to the propellers in advanced turboprop aircraft as well as for existing aircraft configurations. This program summarizes the work carried out at Duke University during the third semester of a contract supported by the Structural Acoustics Branch at NASA Langley Research Center

Adrenergic modulation of potassium metabolism in uremia

Adrenergic modulation of potassium metabolism in uremia. The effect of chronic beta adrenergic blockade on potassium homeostasis during moderate intensity exercise (40% of VO2 max) was examined in seven end-stage renal patients who were being maintained on chronic dialysis treatment. Subjects participated in three study protocols: 1) exercise alone, 2) exercise plus propranolol (a nonselective beta-1, beta-2 antagonist), and 3) exercise plus metoprolol (a specific beta-1 antagonist). The basal potassium concentration was similar in all three studies and averaged 4.95 ± 0.12 mEq/liter. During Study 1 (exercise alone), plasma potassium rose by 0.26 ± 0.09 mEq/liter. During exercise with propranolol, plasma K concentration rose significantly higher (Δ plasma K = 0.44 ± 0.26 mEq/liter; P < 0.05 vs. exercise alone). In contrast, the rise in plasma K during exercise with metoprolol (Δ plasma K = 0.20 ± 0.08 mEq/liter) was similar to that observed with exercise alone. Differences in potassium homeostasis between metoprolol and propranolol could not be explained by differences in hemodynamic parameters, levels of potassium regulatory hormones, or acid base status. Thus, the higher rise in potassium concentration during exercise with propranolol could only be explained by adrenergic blockade at the beta-2 receptor site. These results support the concept that adrenergic control of extrarenal potassium homeostasis in dialysis patients is mediated at the beta-2 receptor. Since a deterioration in potassium homeostasis during exercise is observed with beta-2, but not beta-1 blockade, selective beta-1 adrenergic blocking agents may be safer in dialysis patients

Inactivation of the lysine binding sites of human plasminogen (hPg) reveals novel structural requirements for the tight hPg conformation, M-protein binding, and rapid activation

Accelerated activation of the human plasminogen zymogen (hPg) to two-chain active plasmin (hPm) is achieved following conformational changes induced by ligand-binding at the lysine-binding sites (LBSs) in four of the five hPg kringle domains. In this manner, pattern D skin-trophic strains of Group A streptococci (GAS), through the expression of surface plasminogen-binding M-protein (PAM), immobilize surface hPg, thereby enabling rapid hPg activation by GAS-secreted streptokinase (SK). Consequently, GAS enhances virulence by digesting extracellular and tight cellular junctional barriers using hPm activity. Many studies have demonstrated the singular importance of the kringle-2 domain of hPg (K2hPg) to PAM-binding using hPg fragments. Recently, we showed, using full-length hPg, that K2hPg is critical for PAM binding. However, these studies did not eliminate any modulatory effects of the non-K2hPg LBS on this interaction. Moreover, we sought to establish the significance of the intramolecular interaction between Asp219 of the LBS of K2hPg and its serine protease domain binding partner, Lys708, to conformational changes in hPg. In the current study, selective inactivation of the LBS of K1hPg, K4hPg, and K5hPg revealed that the LBS of these kringle domains are dispensable for hPg binding to PAM. However, the attendant conformational change upon inactivation of K4hPg LBS increased the affinity of hPg for PAM by an order of magnitude. This finding suggests that the native hPg conformation encloses PAM-binding exosites or sterically hinders access to K2hPg. While simultaneous inactivation of the LBS of K1hPg, K4hPg, and K5hPg inhibited hPg/SK association alongside hPg activation, the replacement of Lys708 generated a slight conformational change that optimally accelerated hPg activation. Thus, we accentuate disparate functions of hPg LBS and conclude, using intact proteins, that K2hPg plays a central role in regulating hPg activation

Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide

Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ – O and V5+ – O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient of 85 pm·V−1, and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm−2

Fas/CD95 Deficiency in ApcMin/+ Mice Increases Intestinal Tumor Burden

Fas, a member of the tumor necrosis family, is responsible for initiating the apoptotic pathway when bound to its ligand, Fas-L. Defects in the Fas-mediated apoptotic pathway have been reported in colorectal cancer.In the present study, a variant of the Apc(Min/+) mouse, a model for the human condition, Familial Adenomatous Polyposis (FAP), was generated with an additional deficiency of Fas (Apc(Min/+)/Fas(lpr)) by cross-breeding Apc(Min/+) mice with Fas deficient (Fas(lpr)) mice. One of the main limitations of the Apc(Min/+) mouse model is that it only develops benign polyps. However, Apc(Min/+)/Fas(lpr) mice presented with a dramatic increase in tumor burden relative to Apc(Min/+) mice and invasive lesions at advanced ages. Proliferation and apoptosis markers revealed an increase in cellular proliferation, but negligible changes in apoptosis, while p53 increased at early ages. Fas-L was lower in Apc(Min/+)/Fas(lpr) mice relative to Apc(Min/+) cohorts, which resulted in enhanced inflammation.This study demonstrated that imposition of a Fas deletion in an Apc(Min/+) background results in a more aggressive phenotype of the Apc(Min/+) mouse model, with more rapid development of invasive intestinal tumors and a decrease in Fas-L levels

Inkjet printed doped polyaniline: navigating through physics and chemistry for the next generation devices

Innovative benzidine-free PANI-based inks for electrically conducive inkjet printed devices were developed and tested and the results compared with those obtained by traditional PANI. NMR investigations evidenced the presence of quinones and phenolic groups on the backbone of the innovative PANIs that are thought being responsible for the higher solubility in DMSO. A mechanism of reaction was proposed. The numerous characterizations (NMR, UV-Vis, FTIR, XPS and electrical investigations) allowed to compare protonation level, doping level, valence band maximum for both the type of PANI. The correlation among structural properties, printability, conductivity and solubility was discussed