PubMed Health⌕ Search

Biomedical subjects

Mustafa Akbulut

Publications and source records attributed to Mustafa Akbulut.

5 recordsLinked to original sources
PubMed2026

Genome-wide identification and characterization of 1-amino-cyclopropane-1- carboxylate synthase (ACS) gene family in Carica papaya and expression insights in response to hormone stress.

ACC-synthase (1-aminocyclopropane-1-carboxylate synthase), also known as the ACS gene, plays a pivotal role in ethylene production, which is of great importance in the fruit ripening process for producing saleable yield (marketable fruit). The ACS gene family presumably controls stress responses, plant growth and development, and particularly fruit ripening. Computational biology was used as an essential tool to identify seven ACS genes in Carica papaya (red hermaphrodite) using an RNA-seq database (NCBI GEO). Further, the phylogenetic relationships of ACS genes determined gene family resemblance in the genomes of Hordeum vulgare, Musa acuminata, C. papaya, and Arabidopsis thaliana; therefore, the identified gene families were further classified into four distinct clades (Type-I, Type-II, Type-III, and Type-IV) in alignment with the well-established Arabidopsis classification. Moreover, encompassing gene structure, domain motifs, cis-element phylogenetic profiling, synteny, and transcriptomic profiling unveiled latent structural and functional attributes within CpACS genes. Through segmental duplication of CpACS, insights into evolutionary duplication events were predicted. The paralogous behavior of ACS genes in C. papaya and a comprehensive transcriptomic analysis demonstrated both up- and down-regulation patterns in response to ethylene treatment at different time points during the fruit ripening process, using the papaya manual handbook V2 (2021). Gene expression showed upregulation of two essential CpACS genes, CpACS5 and CpACS6. RT-qPCR validates the expression of these important genes during fruit ripening. However, one gene, CpACS7, is expressed in the later stages of fruit development. Our results demonstrated novel avenues for understanding the expression pathways of the ACS gene family in red hermaphrodite papaya, and most of these genes were linked to regulating various abiotic stresses, plant growth, and fruit development.

Carica↗
PubMed2006

Triboelectrification between smooth metal surfaces coated with self-assembled monolayers (SAMs).

Using a modified surface forces apparatus, we have simultaneously measured the friction and triboelectrification between both similar and dissimilar molecularly smooth hexadecanethiol-coated metal surfaces on mica substrates. On shearing dissimilar surfaces, the tribocurrent increases dramatically as the load or pressure is increased, with large fluctuations about the mean. Neither charge transfer nor fluctuations are observed when the symmetric surfaces are sheared against each other. We also find that the type of friction, i.e., stick-slip or smooth sliding, the load and friction force, the sliding distance, and recent previous history have additional fine influences on the triboelectrification. Our results suggest that frictional dissipation induces electron-hole formation and charge transfer between two shearing surfaces due to molecular-level roughness and defects and local dielectric constant changes, giving rise to the observed tribocurrents.

Journal Article↗
PubMed2006

Friction and tribochemical reactions occurring at shearing interfaces of nanothin silver films on various substrates.

The tribological and tribochemical properties of 5-10 nm thick Ag films sliding on various metal and inorganic substrates were measured using a surface forces apparatus coupled with ex situ x-ray photoelectron spectroscopy. We observed enhanced chemical reactivity in the sheared regions compared to the unsheared regions, which we attribute to significant frictional heating in agreement with two recent simulations. It is also found that the initial topography (roughness) of the films plays a significant role in determining the friction, wear, and tribochemical reactions. The larger the surface roughness, the larger are the friction coefficients. Initially smooth surfaces, forming large continuous junctions, create large wear debris particles; whereas initially rough surfaces, forming many small junctions, create many small particles. Even though initially smooth surfaces are chemically less reactive than initially rough surfaces, they are tribochemically more reactive, forming two to three times more oxides of silver during shearing than under static conditions and organometals of silver that under normal (static) conditions do not form. The chemical reactions observed cannot be explained without including the tribological processes, such as the local stresses, temperature rises, and type of wear produced by the shearing surfaces.

Journal Article↗
PubMed2005

Crystallization in thin liquid films induced by shear.

It is known that the thin-film structure of confined fluids and solids can be changed when the confining surfaces are sheared. Positional and orientational short- or long-range reordering can occur that often have no bulk counterparts. These multilayer, monolayer, or even sub-monolayer effects are important for understanding adhesion and friction processes, but they have proved difficult to measure, partly due to a lack of experimental techniques and partly to their apparent subtle dependence on many experimental parameters. Here we report the use of shear measurements and "optical absorption spectroscopy" in the surface forces apparatus to measure a shear-induced phase transition of an anisotropic (dye) molecule confined between two shearing mica surfaces in aqueous solution. Our studies on the shear-induced ordering and friction forces of highly anisotropic cyanine dye molecules in thin water films show only a weak effect of molecular anisotropy on shear-induced ordering, friction forces, and the onset of shear-induced crystallization, although dramatic changes do occur when the confined molecules ultimately crystallize.

Journal Article↗