Resistant Fraction Research Articles

Experimental behaviour of smart concrete embedded with micro carbon fibres as a sensing material

While there are distinct structural health monitoring methods available, health monitoring using smart concrete is a newly emerging technique. In this technique, cement mortar/concrete is made as self-sensing by introducing carbon fibres in the conventional concrete that can sense strains/stresses/loads. Therefore to study in detail about this technique, in the present research, concrete cubes made from self-compacting concrete of 15 cm size reinforced with carbon fibres in various dosages were cast. Different tests have been performed on sufficient specimens that include stress/strain sensing and crack/damage sensing that resulted in finding co-relation between properties of concrete cube and change fractional resistance (FCR). The obtained results promised that when carbon fibres in the specimen are dosed with 1.5% can give the best co-relation between FCR and concrete cube properties and also the same dosage found to be best suited for stress sensing and crack/damage sensing.

Fractionation of Organic Carbon and Stock Measurement in the Sundarbans Mangrove Soils of Bangladesh

Mangrove soils are well known for their high capacity of storing organic carbon (SOC) in various pools; however, a relatively small change in SOC pools could cause significant impacts on greenhouse gas concentrations. Thus, for an in-depth understanding of SOC distribution and stock to predict the role of Sundarbans mangrove in mitigating global warming and greenhouse effects, different extraction methods were employed to fractionate the SOC of Sundarbans soils into cold-water (CWSC) and hot-water (HWSC) soluble, moderately labile (MLF), microbial biomass carbon (MBC), and resistant fractions (RF) using a newly developed modified-method. A significant variation in total SOC (p ?2 in 1 m soil profile and has an average of 31.80 kg·C·m?2. The substratum soils had more carbon than the upper layers in the Sundarbans wetland due to burial and preservation of carbon by frequent tidal inundation. A higher SOC stock in the soil profile and its primary association in resistant fractions suggested that Sundarbans mangrove soil is sequestering carbon and thereby serving as a significant carbon sink in Bangladesh.

The structural characteristics of amylosucrase-treated waxy corn starch and relationship between its in vitro digestibility.

The glucotransferase amylosucrase (AS) influences the structural properties of starch, but its precise effects are unclear. The structural characteristics and in vitro digestibility of waxy corn starch modified by AS from Neisseria polysaccharea were examined. AS-treated starch exhibited a higher slowly digestible starch (SDS) fraction, the weak B-type polymorph, lower relative crystallinity, and lower double helix content than those of native starches based on X-ray diffractometry, solid-state 13C CP/MAS NMR, and FT-IR. AS-treated starches exhibited increased proportions of degree of polymerization (DP) 25-36 and DP≥37 chains. Higher SDS and resistant (RS) fractions, higher proportions of DP 25-36 and DP≥37 chains, more double helices, higher relative crystallinity, and less difference between double helix and relative crystallinity were observed for starch treated with 460 U than with 230 U of AS. AS re-built the double-helical and rearranged crystalline structure of gelatinized starch and consequently influenced the SDS and RS fractions.

Effects of adrenalectomy on CCD: evidence for differential response of two cell types.

Electrophysiological and chemical methods were used to determine the Na and K transport properties of the isolated cortical collecting duct (CCD) of control and adrenalectomized (ADX) rabbits. Net fluxes of Na (JNa) and K (-JK) in controls were 5.7 and 3.2 pmol . mm-1 . min-1 and in ADX were 1.0 and 0.7 pmol . mm-1 . min-1, respectively, similar to electrically determined rates. In separate experiments, blind impalement of cells from adrenal intact (group 1), ADX (group 2), and ADX rabbits treated with deoxycorticosterone (group 3) allowed identification of two distinct cell types, majority cells (MA) and minority cells (MI). In all groups, MA were distinguished from MI by a relatively high basolateral membrane potential (-Vb), low apical membrane fractional resistance (FRa), and presence of apical and basolateral membrane K conductances. Vb of MA (-82.4 mV) was significantly hyperpolarized in groups 1 and 3 combined, when compared with group 2 (-66.4 mV). However, there was no significant difference between Vb of MI in group 2 (-38.9 mV) and Vb of MI in groups 1 and 3 (-36.2 mV). In MA of group 1 equivalent circuit values of apical membrane Na and K conductances (GNaa, GKa) and maximum pump current (Ipmax) were 0.84 and 6.72 mS/cm2 and 46.7 microA/cm2, respectively. These values in group 2 were significantly lower (0.28 and 1.52 mS/cm2 and 8.7 microA/cm2, respectively). It is concluded that two cell types can be distinguished electrically in the CCD. MA have properties consistent with principal cells and MI have properties consistent with intercalated cells. ADX causes a decrease in GNaa, GKa, and Ipmax of PC that results in proportionate decreases in INaa and IKa.

Evidence for separate cellular origins of sodium and acid-base transport in the turtle bladder

Transmembrane electrical parameters of the epithelial cells in short-circuited turtle bladders were measured to determine whether those cells participating in Na reabsorption also participate in electrogenic transepithelial acidification and alkalinization. Amiloride-induced increases in intracellular potential (Vsca), apical fractional resistance (FRa), and concomitant decreases in short-circuit current (Isc) denote the participation of the impaled cells in Na reabsorption. In bladders from postabsorptive turtles, amiloride increased Vsca by -45 mV, increased FRa by 37%, and decreased Isc from 36 to -10 microA/cm2. In bladders from NaHCO3-loaded turtles, amiloride increased Vsca by -21 mV, FRa by 21%, and decreased Isc from 22 to 0 microA/cm2. Neither the subsequent inhibition of the negative acidification current in postabsorptive bladders, nor stimulation of positive alkalinization current in bladders from NaHCO3-loaded turtles was associated with any transmembrane electrical change that could be attributed to changes in those transport processes. It is concluded that the electrogenic luminal acidification and alkalinization processes of the turtle bladder are not produced by, or electrically coupled to, those cells that are involved in Na reabsorption.

Electrophysiologic changes associated with potassium depletion of frog skin.

Skins from the frog Rana pipiens pipiens were studied under short-circuited conditions during the course of removing and replacing potassium in the inner bathing media in 14 experiments. The intracellular potential (Vsc), fractional resistance (FR), short-circuit current (Isc) and total tissue conductance (gr) were constantly monitored during impalements of the epithelial cells. The mean value (+/- SE) for Vsc was --79 (+/- 3) mV under baseline conditions. Removal of potassium from the inner bathing solution transiently stimulated the short-circuit current and hyperpolarized the basolateral membrane; with sufficiently long incubations, the basolateral membrane was eventually depolarized. Restoration of potassium to the inner solution within 43 min after initiating the perfusion with K+-free solution depolarized the basolateral membrane. However, restoration of potassium after at least 1 1/2 hr of incubation hyperpolarized the membrane. Ouabain consistently depolarized the basolateral membrane, even after extended periods of potassium depletion as long as 320 min. In the presence of ouabain, restoration of potassium depolarized the basolateral membrane. The data provide further evidence for the concept that the Na--K exchange pump of frog skin is rheogenic. Furthermore, the results suggest that the pump continues to be active even during prolonged periods of potassium depletion, reaccumulating potassium which has leaked out of the epithelial cells.