Surface roughness evaluation after machining wear resistant hard coats

The technology HVOF – High Velocity Oxygen Fuel was used to spray the alloy Stellite 6 for the purpose of this research. This method is based on using high velocity spraying flame. The article deals with the evaluation of surface quality after machining of wear resistant hard coats. The goal of the authors was to understand the main factors that influence final surface quality at machining of the coatings from Stellite 6. The findings of experiment have confirmed that there have been obtained very important information about machining of this alloy at the specific type of workpiece. Authors have evaluated the quality of the surface not only by means of Abbott curve, but they have also observed the dependency of arithmetical mean roughness value on both cutting edge radius and feed. The analyses of cutting tips wear at changeable inserts of tools have shown that the typical wear appears in the form of a notch

Surface roughness evaluation after machining wear resistant hard coats

The technology HVOF – High Velocity Oxygen Fuel was used to spray the alloy Stellite 6 for the purpose of this research. This method is based on using high velocity spraying flame. The article deals with the evaluation of surface quality after machining of wear resistant hard coats. The goal of the authors was to understand the main factors that influence final surface quality at machining of the coatings from Stellite 6. The findings of experiment have confirmed that there have been obtained very important information about machining of this alloy at the specific type of workpiece. Authors have evaluated the quality of the surface not only by means of Abbott curve, but they have also observed the dependency of arithmetical mean roughness value on both cutting edge radius and feed. The analyses of cutting tips wear at changeable inserts of tools have shown that the typical wear appears in the form of a notch

Proliferation of Osteoblasts on Laser-Modified Nanostructured Titanium Surfaces

Nanostructured titanium has become a useful material for biomedical applications such as dental implants. Certain surface properties (grain size, roughness, wettability) are highly expected to promote cell adhesion and osseointegration. The aim of this study was to compare the biocompatibilities of several titanium materials using human osteoblast cell line hFOB 1.19. Eight different types of specimens were examined: machined commercially pure grade 2 (cpTi2) and 4 (cpTi4) titanium, nanostructured titanium of the same grades (nTi2, nTi4), and corresponding specimens with laser-treated surfaces (cpTi2L, cpTi4L, nTi2L, nTi4L). Their surface topography was evaluated by means of scanning electron microscopy. Surface roughness was measured using a mechanical contact profilometer. Specimens with laser-treated surfaces had significantly higher surface roughness. Wettability was measured by the drop contact angle method. Nanostructured samples had significantly higher wettability. Cell proliferation after 48 hours from plating was assessed by viability and proliferation assay. The highest proliferation of osteoblasts was found in nTi4 specimens. The analysis of cell proliferation revealed a difference between machined and laser-treated specimens. The mean proliferation was lower on the laser-treated titanium materials. Although plain laser treatment increases surface roughness and wettability, it does not seem to lead to improved biocompatibility

Synthesis of a Pseudodisaccharide α-C-Glycosidically Linked to an 8-Alkylated Guanine

The synthesis of stable guanofosfocin analogues has attracted considerable attention in the past 15 years. Several guanofosfocin analogues mimicking the three constitutional elements of mannose, ribose, and guanine were designed and synthesized. Interest in ether-linked pseudodisaccharides and 8-alkylated guanines is increasing, due to their potential applications in life science. In this article, a novel guanofosfocin analogue 6, an ether-linked pseudodisaccharide connected α-C-glycosidically to an 8-alkylated guanine, was synthesized in a 10-longest linear step sequence from known diol 13, resulting in an overall yield of 26%. The key steps involve the ring-opening of cyclic sulfate 8 by alkoxide generated from 7 and a reductive cyclization of 4-N-acyl-2,4-diamino-5-nitrosopyrimidine 19 to form compound 6

New perfluoroalkylated amphiphilic methacrylates bearing sulfinyl group as monomers for biomedical applications: water content and oxygen permeability of their copolymers with DEGMA

Perfluoroalkylated methacrylates 7a–c bearing sulfinyl group within a straight-chain ester group, i.e. CH2=C(CH3)CO2CH2CH2S(O)–CH2CH2CF2(CF2CF2)nCF3 (n = 1–3) were prepared by two alternative synthetic sequences from 2-[(polyfluoroalkyl)sulfanyl]ethanols HOCH2CH2SCH2CH2CF2(CF2CF2)nCF3 (n = 1–3) in overall yields of 88–91%. Copolymers of 7a–c with diethylene glycol methacrylate (DEGMA) prepared in bulk under radical conditions display high transparency, increased water content and good oxygen permeability properties, which are advantageous for their application in ophthalmology and as prosthetic materials

Heteroatom Analogues of Hydrocodone: Synthesis and Biological Activity

Heteroatom analogues of hydrocodone, in which the <i>N</i>-methyl functionality was replaced with oxygen, sulfur, sulfoxide, and sulfone, were prepared by a short sequence from the ethylene glycol ketal of hydrocodone; a carbocyclic analogue of bisnorhydrocodone was also prepared. The compounds were tested for receptor binding and revealed moderate levels of activity for the sulfone analogue of hydrocodone