all of the tea plantations in iran are concentrated in the caspian sea region on soils previously developed under deciduous natural forests. this research conducted to study the effect of land use change (from forest to tea) on selected physico-chemical and mineralogical properties of soils under humid climate and mountainous landscape in northern iran. three transects facing west to northwest ...

An idealized atmospheric model is employed to quantify the strength of the eddy feedback and the persistence of the zonal index. The strength of the surface frictional damping on the zonal index is varied, and an external zonal momentum forcing is included to compensate for the momentum change associated with the friction change such that the climatological jet latitude and shape are unchanged....

In order to develop methods of designing arti…cial materials of desired tribological characteristics for nano-electromechanical systems (NEMS), a better atomistic understanding of wearless-frictional characteristics of mesoscopic solid materials is indispensable. We have searched for laws of wearless friction accompanying steady sliding motion between mesoscopic crystal lattices, by molecular d...

Scanning force microscopy ~SFM! of topography, frictional force, and stiffness on thin gelatin films reveals an entire spectrum of tribological behavior. Images display two distinct phases of gelatin whose characteristics relate to the degree of crystallinity. Dissimilar regimes of velocityand load-dependent friction and wear on each phase indicate glassy, rubbery, or melt behavior. Of fundamen...

Aim. To compare and evaluate the static frictional resistance offered by the four different types of ligation methods in both dry and wet conditions and at different durations when immersed in artificial saliva. Material and Methods. Alastik Easy to Tie modules, Super Slick Mini Stix elastomeric modules, Power "O" modules, and 0.009(″) Stainless Steel ligatures were used to compare the static f...

We report the results of a direct comparison of the adhesion, friction, and mechanical properties between alkanethiol self-assembled monolayer films terminated by either CH(3) or CF(3) end groups using both interfacial force (IFM) and atomic force (AFM) microscopies. The purpose of this work is to gain insight into the detailed origins of the differing frictional behavior previously observed wi...

The “Leipzig Wind Profile” is a unique example of a representative wind distribution in the frictional layer which resulted from MILDNER’S set of 28 pilot-balloon observations with two theodolites on October 20, 1931, near Leipzig for a stable weather situation. It is shown, that the vectors of geostrophic motion and ground drag follow from the wind profile when a scalar austausch is assumed. T...

INTRODUCTION An elastomeric module with a polymeric coating has been developed to reduce the friction of sliding mechanics. This in-vitro study examined the stability of the coating and compared the frictional properties of coated modules with those of other common ligation methods. METHODS Six ligation methods (regular uncoated, slick [coated], conventional silver, easy-to-tie, silicone-impr...

Low, stable friction, a higher load-carrying capacity, and lower leakage of sealed blood are required for mechanical seals in implantable ventricular assist devices. One solution is to apply surface texture to the mechanical seal surface, consisting of self-mated silicon carbide. However, the effect of surface texture on the frictional properties of mechanical seals under blood sealing conditio...

Background. Any decrease in friction between orthodontic wire and bracket can accelerate tooth movement in the sliding technique and result in better control of anchorage. This study was carried out to evaluate frictional forces by coating orthodontic wires and porcelain brackets with zinc oxide nanoparticles (ZnO). Methods . In this in vitro study, we evaluated a combination of 120 samples of ...