Analysis of Surface Layer Defects on Carburized Steel Component after Alkaline Blackening

Alkaline blackening is one of the most popular surface treatment technology of components with the requirement for higher surface corrosion resistance, increased hardness, and the decorative appearance.This contribution deals with the appearance of surface defects on carburized steel components after the process of alkaline blackening, which appeared to be red shiny stains on an otherwise black matte surface of the component. The occurrence of defects on surface was observed several days after the alkaline blackening process. By means of metallographic methods, direct connection between surface defects and the microstructure of the material was found.Contribution further deals with the influence of microstructure and technological parameters on the quality of the final surface layer of the components.

A Variable Stiffness Joint by Granular Jamming

We propose a novel, high degree of freedom variable stiffness joint for use in a miniature snake-like robot for minimally invasive surgeries via granular jamming. By pulling granule filled membrane-columns under vacuum, the columns and joint stiffen as the granular matter begin to jam. In our experiments, we achieved a four-fold increase in stiffness, and the stiffness can be achieved while the columns are straight or bent. Current flexible manipulators in industrial and medical robotics have followed two dominating methods of actuation and stiffness control. The first method is the continuum manipulator, which utilizes tendons or rods to bend the manipulator in a continuous fashion. The second method is classified as the highly articulated robot, where the manipulator is comprised of multiple segments linked by motor-driven universal joints. Like the latter, our manipulator is highly articulated, however stiffness of each joint can be independently controlled by the granular jamming principle. This paper studies the effect of grain type and vacuum pressure for stiffness tuning. We found that granules with a matte surface were able to achieve higher stiffnesses, with a cube shape exhibiting the highest stiffness, but at the cost of high levels of hysteresis.

Exeter total hip arthroplasty with matte or polished stems

Objective. To compare implant survival rates after total hip arthroplasty with Exeter matte or polished stems and to determine the relationship of synovitis/joint effusion to signs of implant loosening and stem type. Material and methods. The first part of the study included retrospective revision rate analysis of 118 primary hip replacements performed during 1991–1995. Two different designs of Exeter stems were used: matte surface stems during 1991–1995 (matte surface group – 47 cases), and polished stems during 1992–1995 (polished stem group – 71 cases). During the second part of the study, 24 patients (11 in polished stem group and 13 in matte stem group) were prospectively examined with radiography and sonography. Sonography was performed in order to evaluate capsular distension, i.e. the distance between prosthetic femoral neck and anterior capsule. Capsular distension depends on synovitis and/or synovia in prosthetic hip. The relationship between capsular distension, stem type, and radiographic signs of loosening was assessed. Results. For the first part of our study, total implant survival was 78% with matte stems and 61% with polished stems 13 years postoperatively (P=0.27). Stem survival was 82% for matte stems, and 88% for polished stems (P=0.54). In the second part of study, a significant relationship between increased capsular distension and cup loosening was determined (P=0.04). We did not find significant difference in capsular distension when compared matte and polished stems. Conclusion. Implant survival rates did not differ between the groups. The relationship between capsular distension and cup loosening was statistically significant.

Surface color perception in three-dimensional scenes

Researchers studying surface color perception have typically used stimuli that consist of a small number of matte patches (real or simulated) embedded in a plane perpendicular to the line of sight (a “Mondrian,” Land & McCann, 1971). Reliable estimation of the color of a matte surface is a difficult if not impossible computational problem in such limited scenes (Maloney, 1999). In more realistic, three-dimensional scenes the difficulty of the problem increases, in part, because the effective illumination incident on the surface (the light field) now depends on surface orientation and location. We review recent work in multiple laboratories that examines (1) the degree to which the human visual system discounts the light field in judging matte surface lightness and color and (2) what illuminant cues the visual system uses in estimating the flow of light in a scene.

Behavior of adult Simuliidae (Diptera). I. Response to color and shape

Collections of mammalophilic Simuliidae on variously colored and shaped two-dimensional silhouettes indicated that the species oriented to and landed on certain 'preferred' colors. The Prosimulium mixtum/fuscum complex and Cnephia (Stegopterna) mutata were consistently attracted to black targets, the Simulium venustum complex was consistently more attracted to blue silhouettes, and Simulium vittatum oriented and landed on all colored silhouettes except yellow. Black, blue, and red were the most attractive for all species. Colors reflecting the least amount of incident light were the most attractive, a matte surface was more attractive than a glossy one. The response of the flies to simple geometric shapes indicated that all shapes were equally attractive, with the flies aggregating at the points of convergence of the silhouette outline.

A case of healing of the perforated intestine under the Pean's clamping forceps (strangulated hernia)

Abstracts. Surgery."Surgery" v. XIII. No. 73.L. Flerov. A case of healing of the perforated intestine with the Pean's clamping forceps (strangulated hernia).During surgery for a strangulated inguinal hernia, an incarcerated loop of the small intestine, found in a very bad state (matte surface, manifestations of stagnation, initial areas of gangrene), when manipulated to separate the splices, it broke through with a hernia.