Ratio Of Bound Water Research Articles

Leaf functional traits of dominant desert plants in the Hexi Corridor, Northwestern China: Trade-off relationships and adversity strategies

Desert plants are zonal vegetation with unique functional traits and resource trade-offs in arid areas. The trade-off relationship among functional traits and adversity strategies of desert plants play a key role in their community construction. We investigated 16 leaf functional traits of the dominant desert plants, including15 shrubs and 11 herbs, in the Hexi Corridor from southeast to northwest, and analyzed the variation characteristics of traits, trade-off relationship among traits and their responses to soil properties at the regional scale. The results showed that bound water (BW), leaf thickness (LT), and carbon phosphorus ratio (C:P) but total water content (TWC), free water (FW), specific leaf volume (SLV), and specific leaf area (SLA) under shrubs were significantly higher and significantly lower than under herbs, respectively; shrubs’ leaf traits BW and FW ratio (BW:FW), phosphorus content (P), C:P, nitrogen and phosphorus ratio (N:P) had great coefficient of variation, while herbs’ leaf traits BW and N:P had great coefficient of variation. Trade-off among the measured traits was diverse. The TWC, BW, SLV, leaf succulence (Suc), SLA, leaf dry matter content (LDMC) and LT are prominent traits that represent and reflect desert plants under adversity stress. Soil organic carbon (SOC), elevation, pH, soil water content (SW) and sand (0.5-0.25 mm) are important factors influencing the changes of shrubs’ leaf traits, while available phosphorus (AP), SOC, silt (0.02-0.002 mm), sand (0.10-0.05 mm) and clay (<0.002 mm) are dominant factors affecting the changes of herbs’ leaf traits. The results from the present study can provide theoretical support for the maintenance, management and stability of the Hexi Corridor’ ecosystems.

Study of microelement distribution uniformity in a bulk of dough enriched with dietary supplements

The expediency of introduction of dietary supplements based on the chelate complex in food systems and ensuring uniformity of their distribution was substantiated. The objective was to elucidate uniformity of distribution of microelements sorbed on carrier macromolecules and the effect of supplements on functional and technological properties of the dough preparations. Preparations from yeast, puff pastry and unleavened dough with introduced supplements based on the chelate complex were the study subjects. Distribution of the dietary supplement based on the chelate complex in the food system volume and its influence on functional and technological properties of the food systems under study was elucidated. Nuclear magnetic resonance and electron paramagnetic resonance methods, low-temperature calorimetric method and rheological study methods were used.It has been established that powdered supplements based on the stabilized chelate affect mobility and interaction of water molecules with environment of the test dough preparations. It was proved that introduction of metal chelate in the form of a powdered food supplement makes it possible to ensure uniformity of metal distribution in the volume of the preparations under study. It was determined that an increase in amount of chilled water takes place in the dough samples with an introduced dietary supplement based on the chelate complex in comparison with the control samples. The established data indicate growth of amount of bound water provided that a supplement was added. It was noted that the stabilized chelate was mainly in a saturated state since water of the dough preparations was in a «bound» state. A change of elastic properties was established in the test dough preparations with a dietary supplement based on the chelate complex. The obtained results are explained by the change of free to bound water ratio in the food systems under study.The prospects of using powdered supplements with stabilized metal chelates in technologies of food enrichment were proved. It was pointed out that the task of further studies consists in determination of distribution of other microelements of the chelates forming the basis of dietary supplements in the volume of food systems.

DNA compaction determined by energy dissipation measurements on a quartz-crystal oscillator

A quartz-crystal oscillator has been used as a mass measuring device whose resonance frequency decreases linearly on increase of the mass on the oscillator plate. Here, hydration amounts and viscoelastic properties of DNA strands in aqueous solutions were studied by a DNA-immobilized quartz-crystal oscillator connected with a network analyzer for admittance analysis, in which not only resonance frequency changes (?Fwater) but also energy dissipation changes (?Dwater) could be obtained simultaneously in aqueous solutions. Single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) exist as a flexible string structure and vibrate with hydrodynamic water around them under the low ionic condition, indicating a large ?Fwater in comparison with their mass (?Fair as dry mass) on the oscillator. Both DNA strands also showed high energy dissipation (?Dwater) due to their flexible (viscotic) structures in aqueous solutions. When cations such as Na+, spermidine [NH2(CH2)3NH(CH2)4NH2], and Co(NH3)63+ were added, the ?Fwater increased and ?Dwater decreased with increase in cation concentrations, indicating that the DNA was dehydrated and entangled (became elastic) with cations. These effects were in the order of Co(NH3)63+ > spermidine ? Na+. ssDNA was found to form more compact (more dehydrated and more elastic) structures than dsDNA on addition of these cations. The [(??Fwater)/(??Fair) ? 1] and [?Dwater/(??Fair)] values, which reflect the bound water ratio per unit mass and the energy dissipation parameters per unit mass respectively, could be used to characterize conformational changes of the DNA strands.

Ozonolysis pretreatment of maize stover: The interactive effect of sample particle size and moisture on ozonolysis process

Maize stover was ozonolyzed to improve the enzymatic digestibility. The interactive effect of sample particle size and moisture content on ozonolysis was studied. After ozonolysis, both lignin and xylan decreased while cellulose was only slightly affected in all experiments. It was also found that the smaller particle size is better for ozonolysis. The similar water activity of the different optimum moisture contents for ozonolysis reveals that the free and bound water ratio is a key factor of ozonolysis. The best result of ozonolysis was obtained at the mesh of −300 and the moisture of 60%, where up to 75% lignin was removed. The glucose yield after enzymatic hydrolysis increased from 18.5% to 80%. Water washing had low impact on glucose yield (less than 10% increases), but significantly reduced xylose yield (up to 42% decreases). The result indicates that ozonolysis leads to xylan solubilization.

Thermoanalytical investigation of lyotropic liquid crystals and microemulsions for pharmaceutical use

The interactions between surfactant and water were studied thermoanalytically focusing on the lyotropic liquid crystalline and microemulsion region in four ternary systems containing Cremophor EL and Cremophor RH40 as surfactants, neutral oil and isopropyl myristate as oily components. Subzero temperature DSC (SZT-DSC) measurements were carried out to determine the quantity of the bound water forming a hydration layer in surfactant microstructures, and the amount of free water, which has physico-chemical properties not much different from those of pure water. The variation of the surfactant:bound water ratio in the function of water concentration was also investigated. Phase changes detected by the SZT-DSC measurements were confirmed by polarization-microscopic and rheological investigations.

Physico-chemical adhesion and cohesion bonds in joint mortars imparting durability to the historic structures

It is well known that even though historic mortars present low strength and elastic moduli they confer durability to the structures surviving today. The present work investigates the durability of historic mortars in relation to the production technologies employed. Thermal analysis allows for classification of historic mortars in both lime and hydraulic types. Mineralogical data, concerning fabrication and texture, along with thermal analysis provide criteria on specific classification, for: typical lime, crushed brick–lime, cementitious, rubble masonry, hot lime technology and gypsum mortars. The correlation of the measured tensile strength (fmt, k) with the estimated CO 2/structurally bound water ratio, indicates direct proportionality to the levels of the hydraulicity. Physico-chemical adhesion and cohesion bonds, studied by SEM-TEM/EDX, developed at the matrix and at the binder/aggregate interface, respectively, becomes the key factor in interpreting the considerable durability that the historic mortars confer to the structures as bearing elements.