392 research outputs found
Preliminary Investigation of the Frictional Response of Reptilian Shed Skin
Developing deterministic surfaces relies on controlling the structure of the
rubbing interface so that not only the surface is of optimized topography, but
also is able to self-adjust its tribological behaviour according to the
evolution of sliding conditions. In seeking inspirations for such designs, many
engineers are turning toward the biological world to correlate surface
structure to functional behavior of bio-analogues. From a tribological point of
view, squamate reptiles offer diverse examples where surface texturing,
submicron and nano-scale features, achieve frictional regulation. In this
paper, we study the frictional response of shed skin obtained from a snake
(Python regius). The study employed a specially designed tribo-acoustic probe
capable of measuring the coefficient of friction and detecting the acoustical
behavior of the skin in vivo. The results confirm the anisotropy of the
frictional response of snakes. The coefficient of friction depends on the
direction of sliding: the value in forward motion is lower than that in the
backward direction. In addition it is shown that the anisotropy of the
frictional response may stem from profile asymmetry of the individual fibril
structures present within the ventral scales of the reptil
Anatomical variations of the hand extensors
This study was performed to investigate the anatomy and variations of the humanextensor tendons of the fingers and their intertendinous connections. Ninetyfive upper limbs of adult cadavers were dissected. The variations in the extensortendons of the fingers, both proximal and distal to the extensor retinaculum, andtheir mode of insertion were observed. Also, the intertendinous connections wereexplored and the obtained data were analysed. The extensor pollicis longus andbrevis tendons were found to be single, doubled or, rarely, absent. Their insertioncould be traced to either the proximal phalanx, or through the extensor expansionto both phalanges, or rarely to the distal phalanx of thumb. The extensor indicishad a single tendon in all specimens. In the majority of specimens, extensor digitorumhad no independent slip to the little finger; it gave off a single tendonto the index, double tendons to the middle finger and triple tendons to the ringfinger. Extensor digiti minimi muscle often had double or triple tendons distal tothe extensor retinaculum. Three types of juncturae tendinum (JT) were identifiedbetween the tendons of extensor digitorum in the 2nd, 3rd and 4th intermetacarpalspaces (IMS) of hands. Types 1 and 2 JT were seen in the three IMS. Type 3 JTwas the most frequently identified of all juncturae and was always absent in the2nd IMS. The percentages of the present data were compared with other researchers’data
SYNTHESIS OF NOVEL IMIDAZOLE AND FUSED IMIDAZOLE DERIVATIVES AS CYTOTOXIC AND ANTIMICROBIAL AGENTS: MOLECULAR DOCKING AND BIOLOGICAL EVALUATION
Objectives: The objective of this work is to synthesize novel imidazole and fused imidazole derivatives using 5-arylidene-2-hydrazino-3-phenyl imidazolin-4-ones (5a-c) as key intermediate. The structure of the newly synthesized compounds was characterized using IR, 1HNMR, Mass spectroscopy, elemental analysis and some representative 13CNMR.Methods: The target compounds were synthesized starting from 5-arylidene-2-hydrazino-3-phenyl imidazolin-4-ones (5a-c) which prepared from the appropriate 5-arylidene-2-(methylthio)-3-phenyl imidazolin-4-ones (3a-c). Several synthetic pathways were be used for the preparation of the targets. Some of the newly synthesized compounds were evaluated for their cytotoxic activity against breast carcinoma and colon carcinoma cell lines. On the other hand, the antimicrobial activity evaluation of some newly prepared compounds was performed using cup plate diffusion method.Results: Compound 5c was the most active one against breast carcinoma (IC50=3.3 ug/ml) and colon carcinoma cell lines (IC50=4.73 ug/ml) when compared with doxorubicin as standard. Molecular docking studies further supported the highest potency of 5c and further help understanding the various interactions between the ligand and enzyme active sites. On the other hand, the antimicrobial activity evaluation showed that most of the evaluated compounds exhibited broad spectrum activity.Conclusion: The present work led to the development of promising antitumor compounds containing substituted imidazolidin-5-one or imidazotriazol-6-one skeletons. Compounds 5c showed the highest potency at low µg/ml level against breast MCF-7 and colon HCT116 cell lines. On the other hand, most of the newly synthesized compounds showed broad spectrum antimicrobial activity when cup plate diffusion method was performed.Â
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