Polymorphic crystalline wetting layers on crystal surfaces

Analogous to surface premelting, we propose that a crystal surface can undergo a pre-solid-solid transition, i.e. developing a thin polymorphic crystalline layer before reaching the solid-solid transition temperature if two crystals can form a low-energy coherent interface. We confirm this in simulations and colloid experiments at single-particle resolution. The power-law increase of surface layer thickness is analogous to premelting. Different kinetics and reversibilities of surface-crystal growth are observed in various systems. Surface crystals exist not only under thermal equilibrium, but also during melting, crystallization, and grain coarsening. Furthermore, the premelting and pre-solid-solid transition can coexist, resulting double surface wetting layers. We hypothesize that such surface phenomena exist in atomic and molecular crystals, which provide a novel way to tune material properties.

Aerodynamic Investigation of Double Surface Airfoil

Aircraft industry has been deeply concerned about reduction of drag by reducing flow separation and improving the aerodynamic efficiency of flight vehicles, particularly in commercial and military market by adopting various methods. Reduction of flow separation is a concept by which we can increase aerodynamic efficiency. The purpose of the project is to perform an experimental investigation on aerodynamic performance of NACA 0012 airfoil model with and without splits. It is evident from this research work that the airfoil model with split possesses greater aerodynamic performance by producing lesser overall drag. This is due to the delay in flow separation from the surface.

Cylindrical intensive vs. double surface LED phototherapy for neonatal hyperbilirubinemia

Background High bilirubin levels may lead to complications such as bilirubin encephalopathy or even death. Therefore, neonatal hyperbilirubinemia patients require appropriate treatment in the form of phototherapy or exchange transfusion. With the advancement of technology, various types of phototherapy, such as the cylindrical intensive phototherapy (bilisphere) and double LED, are now available. Objective To compare cylindrical intensive phototherapy to double surface LED phototherapy in neonatal hyperbilirubinemia. Methods This cohort study was conducted in neonates with hyperbilirubinemia at at Syamsudin SH Hospital, Sukabumi, West Java, who were treated with either cylindrical intensive phototherapy or double surface LED phototherapy. The variables observed were subjects’ characteristics, bilirubin levels pre- and post-therapy, duration of phototherapy, length of stay, and total treatment cost. The data were analyzed using univariate and bivariate analyses. Results Of 47 neonates, the mean bilirubin levels were 19.36 mg/dL pre-therapy and 12.26 mg/dL post-therapy. Subjects’ overall mean duration of phototherapy was 24 hours, mean length of stay was 1 day, and mean cost of treatment was IDR 813,175. There was no significant difference in the bilirubin decrease between the cylindrical intensive phototherapy and double LED groups. However, there were significant differences between the cylindrical intensive phototherapy and double LED groups in duration of phototherapy (10.75 vs. 75.17 hours, respectively (P<0.000), mean length of stay (1 vs. 3.13 days, respectively (P<0.000), and total cost of treatment (IDR 598,918 vs. IDR 1,036,747, respectively P<0.000). Conclusion While the decrease in bilirubin was not significantly different in neonatal hyperbilirubinemia patients who underwent cylindrical intensive phototherapy compared to double LED therapy, cylindrical intensive phototherapy relates to significant shorter phototherapy duration, length of stay, and total treatment cost. Hence, cylindrical intensive phototherapy phototherapy is considered to be more time-efficient and cost-efficient than double LED phototherapy.

Modern parachute precision aerial delivery systems

The development of parachute precision aerial delivery systems (PADS) has been going on since 1940s. Relying on the analysis of the aerodynamic characteristics of various gliding parachutes, the paper specifies the aerodynamic configuration for modern parachute precision aerial delivery systems, determines the types and considers the possibility of unifying the design of the main parachutes of such systems. The paper describes the history of gliding parachutes, summarizes the experience of developing such parachutes, and considers the evolution of maneuverable and steerable parachutes. In our study, we introduce and substantiate a new for the Russian practice classification of parachutes with aerodynamic quality. First, aerodynamic characteristics of various gliding parachutes were generalized and the main requirements for parachute PADS were indicated. Then, modern combined parachute PADS of Airbone Systems, USA, developed on the basis of double-surface parafoil parachutes were analyzed and classified with the emphasis on the types of modern systems. Since unification is most responsible for reducing the cost of industrial production of any technical systems, we considered the issues of possible unification of parachute PADS. Findings of research show that the unification of modern combined PADS depends on the common elements of control systems. It is worth noting that unification for systems of the ultralight class in terms of main parachutes is possible when using individual parachutes. For parachute systems of the middle and heavy class, intraspecific unification is possible through the use of single parachute modules.

High-power non-perturbative laser delivery diagnostics at the final focus of 100-TW-class laser pulses

Controlling the delivery of multi-terawatt and petawatt laser pulses to final focus, both in position and angle, is critical to many laser applications such as optical guiding, laser–plasma acceleration, and laser-produced secondary radiation. We present an online, non-destructive laser diagnostic, capable of measuring the transverse position and pointing angle at focus. The diagnostic is based on a unique double-surface-coated wedged-mirror design for the final steering optic in the laser line, producing a witness beam highly correlated with the main beam. By propagating low-power kilohertz pulses to focus, we observed spectra of focus position and pointing angle fluctuations dominated by frequencies below 70 Hz. The setup was also used to characterize the excellent position and pointing angle correlation of the 1 Hz high-power laser pulses to this low-power kilohertz pulse train, opening a promising path to fast non-perturbative feedback concepts even on few-hertz-class high-power laser systems.