Solution Uptake Rate Research Articles

Evaluating Various Colors of Persistent Luminescent Powders on Rose Cut Flowers

Rose cut flowers are popular in everyday bouquets or for special occasions, and tinting of the flowers by means of color addition increases the flowers economical value and aesthetic appeal. This study evaluated red and white luminescent rose cut flowers, which was achieved by applying six persistent luminescent powders. Solutions of each color were prepared by mixing 6 g of powder and 240 ml of deionized water and sprayed four times around the flower head plus a control. Images were taken of the flowers before ultraviolet blacklight exposure and after exposure to be later analyzed with ImageJ software. Daily measurements were taken including vase weight, average floral diameter, and visual deterioration based on scale of 1 to 4. Overall measurements included mean brightness; red, green, and blue measured values; dominant wavelengths of emitted color; flower diameter change rate; relative water percent; solution uptake rate; and vase solution uptake rate. For luminescent brightness mean without ultraviolet, white rose with blue powder had the greatest value. For luminescent brightness after ultraviolet exposure, white rose with green powder had the greatest value. With ultraviolet exposure, white roses with green powder had the greatest value followed by blue, orange, and white. Red powder on white and red roses experienced little to no luminescence before or after ultraviolet exposure. Mean and mode varied in their calculated dominant wavelengths; therefore, it is recommended to use mean values because more similarities in matching of the powder color and the calculated dominant wavelength were reported. Ultimately, white roses are preferred because they seemed to have greater health and luminescence compared with red roses, and green and blue powder would be recommended for luminescent application for brightness.

Vase life consequences of natural and chemical treatments in foxtail lily (Eremurus spectabilis), as a specialty cut flowers

Abstract Eremurus spectabilis is a new, commercially valuable specialty cut flower, but little is known about the applicable treatments to extend the vase-life and maintaining the ornamental quality of this flower. Therefore, the present study was aimed at investigating the impacts of nano-silver, essential oils, and chemical treatments on keeping ornamental quality and vase-life of cut inflorescences of Foxtail lily. The cut inflorescences were placed in different vase solutions containing salicylic acid (100 and 200 mg L-1), methyl jasmonate (25 and 50 mg L-1), silver thiosulfate (0.1 mM) plus isothiazolinone (0.001 and 0.005 mL L-1), nano-silver (5, 10, and 15 mg L-1), thymol (75 and 120 mg L-1), and menthol (75 and 120 mg L-1), which were applied as continuous and pulsing methods. According to the results, all treatments considerably improved the post-harvest performance of Foxtail lily cut flowers. Although there were no significant differences among nano-silver (NS) treatments, the cut inflorescences kept in vase solution containing 10 mg L-1 of NS exhibited the longest vase life (~14 days) and the best ornamental quality. Nano-silver treatment followed by silver-thiosulfate significantly improved solution uptake by flowering inflorescences, thereby delaying the water balance loss and keeping relative fresh weight. Furthermore, 50 mg L-1 methyl jasmonate- and 75 mg L-1 menthol-treated cut inflorescences exhibited significantly higher vase-life longevity by ~ 6 and 4 days, total soluble solutes by 28.38% and 19.12%, and solution uptake rate by 76.46% and 140.6%, respectively, as compared to control. Overall, 10 mg L-1 NS can be recommended as a commercial preservative solution to delay flower senescence and improve the vase life and keeping the quality of foxtail cut inflorescence.

Reactive transport modelling the oxalate-carbonate pathway of the Iroko tree; Investigation of calcium and carbon sinks and sources

The oxalate carbonate pathway (OCP) of the Iroko tree has been shown to function as a carbon sink, due to the precipitation of calcium (Ca) carbonate in the tree and the soil around its roots, a soil developed on a carbonate-free bedrock. A 1D reactive transport (RT) model of the Iroko OCP system was constructed and used in a sensitivity analysis to replicate the geochemical pathway of the OCP and carbon sequestration, constrained by the Ca mass balance. The sensitivity analysis examined ranges of contributions for Ca sources to the system, including rainfall, dust, plant decomposition, mineral weathering, and optionally groundwater Ca sources. The study focused on identifying possible scenarios by which the observed magnitude of accumulated soil calcite could be reproduced, related to the OCP geochemical pathway. In line with field observations of the Iroko, all model results showed a soil transition from acidic (pH 5.1) to mildly alkaline (maximum pH 8.1) conditions, as well as precipitation of calcite. The location of calcite precipitation remained within the upper reach of the soil column, and between 29% and 63% of carbon was retained as calcite. The magnitude of calcite precipitation was limited both by the availability of Ca from the various sources, and by the tree’s rate of root water and solute uptake. The sensitivity analysis confirms that surficial sources such as rainfall and dust deposition contribute only a small fraction of Ca, and indicate that mineral weathering and the extent of the root system, must play a dominant role in supplying Ca to facilitate carbon sequestration through calcium carbonate formation.

INFLUENCE OF BLUE AND RED LEDs ON DEVELOPMENT AND NUTRITIVE VALUE OF PERILLA FRUTESCENS (L.) CULTIVATED IN CLIMATE CHAMBERS

In this study influence of supplemental blue and red LED lighting on growth, nutrient solution uptake and concentration of secondary metabolites was investigated. Perilla plants were cultivated in climate chambers, where main light was provided by fluorescent tubes with PPFD between 123-177 μmolm-2s-1. Additionally, blue and red LEDs were used, providing 11 μmolm-2s-1 or 12 μmolm-2s-1, respectively. Temperature was set on 24/19°C (day/night), relative air humidity on 64/56% (day/night), and day length was 16 hours. Results showed that small portion of supplemental blue light (~9%) increased fresh mass (FM), dry mass (DM), and nutrient solution uptake (NSU) up to 50.33%, 10.85% or 31.80%, respectively. Supplemental red light (~6%) increased nutrient solution uptake up to 23.56%, while fresh and dry mass were higher than control, but without statistical significance. Regarding nutritive value of Perilla, supplemental blue light significantly increased carotenoid concentration (Car) (+13.37%), but polyphenols (PP), anthocyanins (Anth) and flavonoid (Fl) concentrations did not differ from the control. In treatment with supplemental red light, only flavonoid concentration was significantly increased (+14.34%). Use of supplemental blue or red LEDs in closed systems with controlled conditions increase or tends to increase plants fresh mass, dry mass, nutrient solution uptake rate, as well as concentration of some secondary metabolites.

EFFECT OF SOME BIOCIDES ON THE VASE LIFE OF CARNATION (DIANTHUS CARYOPHYLLUS L.) CUT FLOWERS

The current study was carried out at Antoniades Research Branch, Ornamental Plants and Landscape Gardening Res. Dept., Hort. Res. Inst., ARC, Alexandria, Egypt, over two consecutive seasons of 2019 and 2020. The aim of this study was to compare the effects of silver nitrate (AgNO3) at (20, 30, and 40 mg l-1), 8-hydroxyquinoline sulfate (8-HQS) at (50, 100, and 200 mg l-1), citric acid (CA) at (50, 100, and 150 mg l-1) and salicylic acid (SA) at (100, 150, and 200 mg l-1) as holding preservative solutions for reducing bacterial decay and prolonging the vase life on cut carnation (Dianthus caryophyllus L.) flowers. The following records were evaluated at the conclusion of the experiment: vase life (days), which was calculated as the number of days before the flowers started to wilt, loss of flower fresh weight percentage (LFFW percent), final water uptake (g), flower fresh weight/flower dry weight ratio (FWR), relative fresh weight, vase solution uptake rate, and several chemical component tests. The results showed that the highest significant improvement in most measurements were obtained when treated with silver nitrate AgNO3 at a concentration of 30 mg l-1 including improved vase life, final water uptake, flower fresh weight/flower dry weight ratio, chlorophyll a & b, carotene content, and sugars content. It also reduced the number of bacterial colonies in the vase water. The treatment with 8-hydroquinoline sulfate at 200 mg l-1 was the closest to that treatment in most of the studied characteristics

Using Arachis pintoi leaf extracts in biosynthesis of silver nanoparticles for improving the vase life of cut carnation (Dianthus caryophyllus L.)

A biological method for synthesizing silver nanoparticles (SNPs) using the leaf extracts of Arachis pintoi Krapov. & W.C. Greg. was developed. The optimum conditions of input materials were found with leaf autoclaving in 15 min, 20 g fresh leave, and 4 mM of silver nitrate (AgNO3). To study the role of time, temperature, and solution pH of the reaction, varying time reaction (5, 30, 60, 90, 120, 150, and 180 min), temperature reaction (10, 20, 30, 40, and 50oC) and pH of the solution (1, 3, 5, 7, 9, and 11) were investigated. The optimal biosynthesis conditions were achieved in 180 min of reaction time at 50oC and pH 11. The obtained nanoparticles have spherical and oblong in shape with average size of 26.4 nm. The SNPs in 4 concentrationss (5, 15, 25, and 35 ppm) combined with and without 2% sucrose extended vase life, enlarged flower diameter, and maintained increase the relative fresh weight with vase solution uptake rate. SNPs inhibited significantly the bacterial growth in the stem end and vase solution, reduced the blockage in stems and therefore promoted the postharvest quality of carnation cut flowers. Out of the treatments, administration of 5 ppm SNPs with 2% sucrose of vase solution gave the best results for all parameters. The biosynthesis SNPs could be applied as a promising preservative solution for carnation cut flowers.

Chain length and acidity of carboxylic acids influencing adsorption/desorption mechanism and kinetics over anion exchange membrane

Selective recovery of carboxylic acids through anion exchange membrane (AEM) during electrodialysis (ED) involves bulk transport/diffusion/adsorption/desorption steps. Combined effect of size, structure, percentage dissociation, interactions alter each step of transport. In this study, we focused on interpretation of role of functional groups (number of COOH groups) and hydrocarbon chain length of different carboxylic acids (formic (FA), acetic (AA), propionic (PA), butyric (BA), malic (MA) and citric (CA) acids) during their transport in terms of ion interaction with membrane. Quantitative estimate of interactions between acids – AEM, adsorption mechanism and solute uptake rate were inferred from adsorption isotherms (Langmuir, Freundlich and Redlich-Peterson) and kinetic models (pseudo-first-order, pseudo-second-order and Elovich). Adsorption was rate limiting and Freundlich isotherm was more appropriate. Adsorption capacities, Kf followed an order: 0.139 > 0.121 > 0.072 > 0.062 > 0.049 > 0.025 mmol·g−1 respectively with CA, MA, FA, AA, PA, BA. Pseudo-second order rate constants, k2 followed same order of adsorption, highest with CA (0.0187 g·mmol−1 min−1) and lowest with BA (0.0124 g·mmol−1 min−1) and dominance of heterogeneous mode of chemical/ionic interactions. pKa, chain length and molecular sieve effects were used to support the adsorption pattern.

Quantifying the impact of tissue metabolism on solute transport in feto-placental microvascular networks.

The primary exchange units in the human placenta are terminal villi, in which fetal capillary networks are surrounded by a thin layer of villous tissue, separating fetal from maternal blood. To understand how the complex spatial structure of villi influences their function, we use an image-based theoretical model to study the effect of tissue metabolism on the transport of solutes from maternal blood into the fetal circulation. For solute that is taken up under first-order kinetics, we show that the transition between flow-limited and diffusion-limited transport depends on two new dimensionless parameters defined in terms of key geometric quantities, with strong solute uptake promoting flow-limited transport conditions. We present a simple algebraic approximation for solute uptake rate as a function of flow conditions, metabolic rate and villous geometry. For oxygen, accounting for nonlinear kinetics using physiological parameter values, our model predicts that villous metabolism does not significantly impact oxygen transfer to fetal blood, although the partitioning of fluxes between the villous tissue and the capillary network depends strongly on the flow regime.

Potential of agro-waste sugarcane bagasse ash for the removal of ammoniacal nitrogen from landfill leachate.

Ammoniacal nitrogen is considered as one of the major pollutants of the leachate generated from the landfill site and has the potential to deteriorate the environment as well as health. Considering this, locally available agricultural waste, i.e., sugarcane bagasse ash, was employed as an adsorbent for the removal of ammoniacal nitrogen from landfill leachate. Batch-mode experiments were conducted to see the effect of dose (2-60 g L-1), pH (2-12), and temperature (20-60 °C) on ammoniacal nitrogen adsorption. Application of sugarcane bagasse ash showed 60% removal of ammoniacal nitrogen (50 mg L-1 strength) at an optimum dose of 20 g L-1 and 180 min of contact time with an adsorption capacity of 0.31 mg g-1. The Langmuir adsorption model was found to be best fit at 40 °C with R2 = 0.944, depicting a monolayer coverage of ammoniacal nitrogen onto sugarcane bagasse ash. According to the result, solute uptake rate could be well described by the pseudo-second-order model (R2 = 0.928), whereas the intraparticle diffusion model and Boyd plot indicated that the overall adsorption rate is governed by the external mass transfer. Thermodynamic studies revealed that adsorption is feasible, spontaneous, and endothermic in nature. Hence, the study shows that sugarcane bagasse ash could turn out to be a cost-effective adsorbent for the removal of ammoniacal nitrogen from leachate.

Postharvest characteristics of two flowering stages of torch ginger (Etlingera elatior) inflorescences

Torch ginger (Etlingera elatior), a flourish in tropical and subtropical climates crop, with extravagant and showy inflorescence may be used as cut flower at each developmental stage. Limited studies have been undertaken to reveal the postharvest performance of this leafless inflorescence, especially at advanced developmental stages. Therefore, the objective of this study was to elucidate the postharvest performance of the torch ginger inflorescence treated with different vase solutions. Inflorescences at two flowering stages i.e., tight bud stage and torch shows stage at about 35 and 58 days, respectively, after emergence from rhizome, were used in this study. Sucrose (20 g L-1), 8-hydroxyquinoline sulfate (8-HQS, 0.1 g L-1) and distilled water were used as vase solution treatment. Postharvest characteristics, including vase life, relative fresh weight (RFW), dry weight, solution uptake rate, respiration and ethylene production rate were evaluated. Results showed that vase life of tight bud stage inflorescence was significantly higher than torch shows stage irrespective of treatments used. In contrast, significantly higher solution uptake rate was shown in the torch shows stage inflorescence. There was no significant difference in dry weight and respiration rate measured. No ethylene was detected in all treated inflorescences throughout the study. Prolongation of vase life was associated with the increase in RFW. Increase of RFW was found in tight bud stage inflorescence but reduction of RFW was shown in torch stage inflorescence at the end of vase life. The decrease of RFW could be due to the breakdown of stored carbohydrates in peduncle for the development of true flowers for pollination purpose. Supplementation of sucrose promoted the opening of true flowers. The use of 8-HQS and distilled water enabled the development of true flowers, but they failed to open. Sucrose treated inflorescences both in tight bud and torch stage showed better postharvest quality compared to 8-HQS and distilled water.

Effect of different vase solutions on postharvest longevity of cut foliage <i>Ophiopogon</i> <i>japonicus</i>

Ophiopogon japonicus (L.f.) Ker-Gawl (family Liliaceae) is an export-oriented foliage plant with attractive white-green strips. The vase life of this cut foliage ends when the leaves loose turgidity and/ or bright green colour. Thus, to enhance the vase life of O. japonicus, effect of 0.25, 0.5, and 1.0 mM CuSO4.5H2O, 10, 20, and 30 g/L sucrose and combination of sucrose with 0.5 mM CuSO4.5H2O as holding treatments, 20 g/L and 30 g/L sucrose solutions as 24 h pulsing treatments and 6-Benzylaminopurine 5, 10, 20 mg/L BAP were tested. Relative fresh weight of leaves, solution uptake rate and vase life were assessed. Vase solution bacterial enumerations were carried out to evaluate the effectiveness of CuSO4.5H2O as a biocide. To investigate the function of BAP, amount of chlorophyll was quantified using leaf pigment extracts. The vase life of O. japonicus could be extended from 5.1 days to 12.5 days by giving BAP based vase solutions. Chlorophyll contents of leaves dipped in BAP solutions were significantly higher than the control (distilled water). CuSO4 solutions did not show any significant antibacterial effects compared to the control. According to vase life data, the most effective vase solutions were CuSO4.5H2O (0.5 mM), sucrose 20 g/L with CuSO4.5H2O (0.5 mM) as holding treatments, sucrose 20 g/L and 30 g/L as pulsing treatments and BAP treatments (5, 10, 20 mg/L).

Postharvest Longevity of Cut Gerbera and Alstroemeria as Affected by Citric Acid Pulse and Vase Solutions

End-user vase life of two popular cut flowers, gerbera (Gerbera jamesonii) and alstroemeria (Alstroemeria spp.) is limited due to non-adoption of appropriate postharvest treatments in Sri Lanka. Citric acid-based cut flower preservatives could be affordable treatments to extend the longevity of those species. Therefore, a study was carried out to investigate the effectiveness of pulse and vase solution treatments with citric acid for increasing the keeping quality of cut gerbera and alstroemeria flowers. For pulsing, cut flower stems were treated with 0 mM (distilled water), 5, 10 and 15 mM citric acid combined with 5, 16 and 24 h pulsing durations. Only alstroemeria was further tested with 0, 15, 25 and 30 mM citric acid with previous pulsing durations. Pulsed stems were stood into distilled water for vase life evaluation. For vase solution treatment, citric acid at 0, 1, 2, 5 and 10 mM concentrations were incorporated in vase water. In the next step, two levels of citric acid (0, 1 mM) were combined with four levels of sucrose (0, 1, 2, 5%) in vase water for gerbera. Factorial experiments were arranged in completely randomized design with five to ten replicates. Data on vase life, relative fresh weight and solution uptake rate were recorded. Pulse treatments were ineffective for improving vase life. Nevertheless, a vase solution with 1 mM citric acid showed a 2-fold increase in vase life and a better retention of fresh weight in cut gerbera. Incorporation of citric acid in vase water did not extend the vase life of cut alstroemeria flowers. Combining citric acid with sugar in the vase solution maintained favourable relative fresh weight, water uptake rates and vase life in cut gerbera. Thus, incorporation of 1 mM citric acid and 1 – 2 % sugar in vase or holding solutions could improve the longevity of cut gerbera flowers.

Salicylic acid and jasmonic acid treatments for potentially extending the longevity of cut Acacia holosericea foliage

ABSTRACTAcacia holosericea is a novel cut foliage line with a short vase life. Postharvest application of salicylic acid (SA) can extend the vase life of cut flower. SA is a host defence inducer, as is jasmonic acid (JA). SA and JA were compared as vase solution additives for A. holosericea. Three experiments were conducted that also compared these two chemicals with H+ and Cu2+ as known vase life extending additives. Vase solutions containing SA at 0.5, 1.5, and 2.5 mM gave ~1.3- to 1.5-fold vase life extensions as compared with the distilled water (DW; control). Provision of Cu2+ and JA at 0.5 mM in vase solutions also prolonged vase life by ~1.3-fold as compared with DW. The positive effect of SA tended to be greater than that of JA, but was inferior to that of Cu2+ at the same concentration. However, trend differences among these treatments were not statistically significant. Cut A. holosericea foliage stems treated with SA and JA exhibited higher relative fresh weight (RFW) and vase solution uptake rates as compared with DW. Overall, SA and JA evidently extended the vase life of cut A. holosericea foliage by inhibiting water loss and maintaining RFW during the vase period.

Effect of plant bioregulators on the vase life of snapdragon (Antirrhinum majus) cut flowers

The present study on effect of plant bioregulators on the vase life of snapdragon (Antirrhinum majus L) cut flowers was conducted at Directorate of Floricultural Research, Pusa Campus, New Delhi during 2013-14 to evaluate snapdragon flower spikes as cut flower based on vase life and the effect of plant bioregulators on the vase life of snapdragon flower. Plant bioregulators namely aminooxyacetic acid (AOA) 0.5mM, salicylic acid (SA) 1mM and benzyl adenine (BA) 0.2mM along with 2% sucrose was evaluated. Vase life of snapdragon flower spikes were significantly increased in treatments with plant bio regulators BA+ sucrose, SA + sucrose and AOA + sucrose (9.3, 9 and 8.3 days) in comparison with control (5.6 days) and sucrose (2%) alone (7.3days). Treatments with plant bioregulators delayed the flower opening and flower senescence. Change in fresh weight was less in treatments with plant bioregulators and vase solution uptake rate was also more in the same treatments when compared to Control. Membrane stability index of spikes treated with BA + sucrose was better (64.99%) after 9 days of experiment. Bract chlorophyll content and petal carotenoid content after 9 days of vase life were found better in BA+ sucrose treatment (3.2 mg/g and 0.896 mg/ g/respectively). BA performed better than other bio regulators in terms of vase life, colour retention and membrane stability. Sucrose (2%) alone improved the vase life but not significant when compared with solutions containing plant growth regulators along with it.

Atmospheric Pressure Glow Discharges Generated in Contact with Flowing Liquid Cathode: Production of Active Species and Application in Wastewater Purification Processes

Miniaturized atmospheric pressure glow discharges (APGDs) were generated in contact with small sized flowing liquid cathode systems. As anodes a solid pin electrode or a miniature flow Ar microjet were applied. Both discharge systems were operated in the open to air atmosphere. Hydrogen peroxide (H2O2) as well as ammonium (NH4 +), nitrate (NO3 −), and nitrite (NO2 −) ions were quantified in solutions treated by studied discharge systems. Additionally, an increase in the acidification of these solutions was noted in each case. Emission spectra of the near cathode zone of both systems were measured in order to elucidate mechanisms that lead to the formation of active species in gas and liquid phases of the discharge. Additionally, the concentration of active species in the liquid phase (H2O2, NH4 +, NO3 − and NO2 −) was monitored as a function of the solution uptake rate and the flow rate of Ar. The suitability of investigated discharge systems in the water treatment was tested on artificial wastewaters containing an organic dye (methyl red), hardly removable by classical methods non-ionic surfactants (light Triton x-45 and heavy Triton x-405) and very toxic Cr(VI) ions. Preliminary results presented here indicate that both investigated flow-through APGD systems may successfully be applied for the efficient and fast on-line continuous flow chemical degradation of toxic and hazardous organic and inorganic species in wastewater solutions.

Effect of Sodium Nitroprusside on Vase Life and Postharvest Quality of a Cut Rose Cultivar (Rosa hybrida ‘Utopia’)

This experiment was carried out to investigate the effect of sodium nitroprusside (SNP) as a nitric oxide (NO) donor compound on postharvest life of a cut rose cultivar (Rosa hybrida ‘Utopia’). At laboratory with 21 ± 2ºC temperature, 70% relative humidity, and 12h photoperiod, flowers were treated with SNP (0 (Control = Distilled water), (50 and 100 µMolar) solutions for 24 hours and then were transferred to distilled water and were held in distilled water until the end of the vase life. Soluble protein content, solution uptake rate, relative fresh weight, total chlorophyll (a+b) content, and vase life of flowers were determined. Results showed that flowers treated with 50 µMolar SNP had more soluble protein content compared to control. SNP (50 µMolar) application increased solution uptake rate of flower stems. Also flowers treated with 50 µMolar SNP had more relative fresh weight compared to control significantly. SNP (50 µMolar) increased vase life of cut rose ‘Utopia’ from 11 days (control) to 13.3 days.

Effect of Root Water and Solute Uptake on Apparent Soil Dispersivity: A Simulation Study

Plants take up water from the root zone and thus affect the three-dimensional water flow field and solute transport processes in the soil. In this study, the impacts of root architecture, plant solute uptake mechanisms (passive, active, and solute exclusion), and plant transpiration rate on the water flow field in the soil and on solute spreading were simulated. Therefore, a fully mechanistic model was used to simulate water flow along water potential gradients in the root–soil continuum by coupling a three-dimensional Richards equation in the soil with a flow equation in the root xylem vessels. Solute transport was simulated using a three-dimensional random walk particle tracking algorithm. To quantify the effect of root water and nutrient uptake on solute transport, an equivalent one-dimensional flow and transport model was fitted to horizontally averaged simulation results, and the fitted apparent parameters were compared with the parameters of the three-dimensional model. Our simulation results showed that the apparent dispersivity length is affected by the heterogeneous flow field, caused by root water uptake, and changed in a range of 50%, depending on solute redistribution in the root zone that depends on solute uptake type and soil dispersivity length. In addition, simulation results indicate that local concentration gradients within the root zone have an impact on apparent solute uptake rate parameters used in one-dimensional models to calculate uptake rates from spatially averaged concentrations. This shows the importance of small scale three-dimensional water and solute fluxes induced by root water and nutrient uptake.

An analytical performance of atmospheric pressure glow discharge generated in contact with flowing small size liquid cathode

A dc atmospheric pressure glow discharge (APGD) operated in open air atmosphere was applied as a miniaturized excitation source in analytical optical emission spectrometry. The discharge was generated in contact with a small size liquid cathode of a novel design and stably operated at a low current (20 mA) and solution uptake rate (0.6 mL min−1). The volume of the discharge was estimated to be ∼6 mm3, while the power density was ∼5 kW cm−3. For the selected elements, i.e., Ca, Cd, Cu, K, Li, Mg, Mn, Na, Rb and Zn, the detection limits, the dynamic linearity ranges and the precisions were determined to ascertain the analytical performance of this miniaturized excitation source. The concentrations of some elements (Ca, K, Mg, Mn, Na and Zn) were determined in the samples of tea and its infusions and mineral water. These results were compared to those obtained by flame atomic absorption spectrometry (FAAS) and flame atomic emission spectrometry (FAES) and a good agreement between the results was established. Additionally, the effect of the easily ionizable elements (EIEs) on the relative intensities and the signal to background ratios (SBRs) of the measured emission lines as well as the Mg II/Mg I ratio and electron number density were investigated.

Effect of Dynamic Loading on the Transport of Solutes into Agarose Hydrogels

In functional tissue engineering, the application of dynamic loading has been shown to improve the mechanical properties of chondrocyte-seeded agarose hydrogels relative to unloaded free swelling controls. The goal of this study is to determine the effect of dynamic loading on the transport of nutrients in tissue-engineered constructs. To eliminate confounding effects, such as nutrient consumption in cell-laden disks, this study examines the response of solute transport due to loading using a model system of acellular agarose disks and dextran in phosphate-buffered saline (3 and 70 kDa). An examination of the passive diffusion response of dextran in agarose confirms the applicability of Fick's law of diffusion in describing the behavior of dextran. Under static loading, the application of compressive strain decreased the total interstitial volume available for the 70 kDa dextran, compared to free swelling. Dynamic loading significantly enhanced the rate of solute uptake into agarose disks, relative to static loading. Moreover, the steady-state concentration under dynamic loading was found to be significantly greater than under static loading, for larger-molecular-mass dextran (70 kDa). This experimental finding confirms recent theoretical predictions that mechanical pumping of a porous tissue may actively transport solutes into the disk against their concentration gradient. The results of this study support the hypothesis that the application of dynamic loading in the presence of growth factors of large molecular weight may result in both a mechanically and chemically stimulating environment for tissue growth.

Analysis of nickel concentration profiles around the roots of the hyperaccumulator plant Berkheya coddii using MRI and numerical simulations

Investigations of soil-root interactions are hampered by the difficult experimental accessibility of the rhizosphere. Here we show the potential of Magnetic Resonance Imaging (MRI) as a non-destructive measurement technique in combination with numerical modelling to study the dynamics of the spatial distribution of dissolved nickel (Ni2+) around the roots of the nickel hyperaccumulator plant Berkheya coddii. Special rhizoboxes were used in which a root monolayer had been grown, separated from an adjacent inert glass bead packing by a nylon membrane. After applying a Ni2+ solution of 10 mg l−1, the rhizobox was imaged repeatedly using MRI. The obtained temporal sequence of 2-dimensional Ni2+ maps in the vicinity of the roots showed that Ni2+ concentrations increased towards the root plane, revealing an accumulation pattern. Numerical modelling supported the Ni2+ distributions to result from advective water flow towards the root plane, driven by transpiration, and diffusion of Ni2+ tending to eliminate the concentration gradient. With the model, we could study how the accumulation pattern of Ni2+ in the root zone transforms into a depletion pattern depending on transpiration rate, solute uptake rate, and Ni2+ concentration in solution.