Concentrations In Compartments Research Articles

The virtual cell based assay: Current status and future perspectives

In order to replace the use of animals in toxicity testing, there is a need to predict in vivo toxic doses from concentrations that cause toxicological effects in relevant in vitro systems. The Virtual Cell Based Assay (VCBA) estimates time-dependent concentration of a test chemical in the cell and cell culture for a given in vitro system. The concentrations in the different compartments of the cell and test system are derived from ordinary differential equations, physicochemical parameters of the test chemical and properties of the cell line. The VCBA has been developed for a range of cell lines including BALB/c 3T3 cells, HepG2, HepaRG, lung A459 cells, and cardiomyocytes. The model can be used to design and refine in vitro experiments and extrapolate in vitro effective concentrations to in vivo doses that can be applied in risk assessment. In this paper, we first discuss potential applications of the VCBA: i) design of in vitro High Throughput Screening (HTS) experiments; ii) hazard identification (based on acute systemic toxicity); and iii) risk assessment. Further extension of the VCBA is discussed in the second part, exploring potential application to i) manufactured nanomaterials, ii) additional cell lines and endpoints, and considering iii) other opportunities.

The Fate of Cu, Zn and Mn in an Intensive Fish Aquaculture (Tilapia - Oreochromis niloticus) in an Artificial Reservoir in Northeastern Brazil

Emissions of Cu, Zn and Mn and their fate in a typical tilapia (Oreochromis niloticus) cage farm in an artificial reservoir in northeastern Brazil were estimated through the analysis of their concentrations in the various compartments of the farm. Major source of Cu and Zn, but not of Mn, to the farm is from aquafeeds, with annual inputs of 3.83, 57.50 and 10.95 kg.ha−1, respectively. Notwithstanding, only a small fraction of the added Mn and Zn (0.13%, 2.61%, respectively) is incorporated into fish biomass, resulting in a larger proportion of the introduced metals to be exported to reservoir environment. For Cu, a much larger fraction (47.4%) is exported within the fish biomass. Once released, metals are incorporated into bottom sediments within the farm area, resulting in higher metal contents compared to sediments far from the farm area. However, the analysis of sediment cores and the respective enrichment factors showed that a significant fraction of the net input of Zn (70%) and of Cu (30%) is exported out to the open reservoir.

Zinc and metalloproteinases 2 and 9: What is their relation with breast cancer?

Zinc is the catalytic component of proteins that regulate responses to DNA damage, intracellular signaling enzymes, and matrix metalloproteinases, which are important proteins in carcinogenesis. The objective of this review is to bring current information on the participation of zinc and matrix metalloproteinases types 2 and 9 in mechanisms involved in the pathogenesis of breast cancer. We conducted a literature review, in consultation with the PubMed, Lilacs, and Scielo databases. The zinc and cysteine residues are structural elements shared by all members of the family of matrix metalloproteinases, and these proteins appear to be involved in the propagation of various types of neoplasms, including breast cancer. Moreover, transported zinc is likely to be used for the metalation of the catalytic domain of the newly synthesized metalloproteinases before the latter are secreted. Accordingly, increase in zinc concentrations in cellular compartments and the reduction of this trace element in the blood of patients with breast cancer appear to alter the activity of metalloproteinases 2 and 9, contributing to the occurrence of malignancy. Thus, it is necessary to carry out further studies with a view to clarify the role of zinc and metalloproteinases 2 and 9 in the pathogenesis of breast cancer.

Pharmacodynamic principles and the time course of immediate drug effects.

This tutorial defines the principles of the concentration - effect relationship which are the basis of pharmacodynamics. The two key parameters of pharmacodynamics are the maximum response (Emax) and the concentration producing 50% of Emax (C50). The time course of effect is illustrated under the assumption that drug effects are immediately related to concentration in the central compartment e.g. plasma. The related idea of duration of drug action and its relationship to dose is shown to have a simple relationship with drug half-life.

Semiempirical kinetic modelling of water desalination by electrodialysis processes

ABSTRACTWater desalination was performed by electrodialysis (ED) in batch recirculation mode by means of cationic and anionic membranes containing sulfonate and ammonium groups, respectively. Variations in sodium chloride (NaCl) concentration in dilute compartment versus time during ED experiments were recorded at different voltages, flow rates, and feed concentrations. ED experiments were modelled by means of a semiempirical kinetic model. A good agreement is found between experimental data and the model.

Increased total sodium concentration in gray matter better explains cognition than atrophy in MS.

To investigate whether brain total sodium accumulation assessed by 23Na MRI is associated with cognitive deficit in relapsing-remitting multiple sclerosis (RRMS). Eighty-nine participants were enrolled in the study (58 patients with RRMS with a disease duration ≤10 years and 31 matched healthy controls). Patients were classified as cognitively impaired if they failed at least 2 tasks on the Brief Repeatable Battery. MRI was performed at 3T using 23Na MRI to obtain total sodium concentration (TSC) in the different brain compartments (lesions, normal-appearing white matter [NAWM], gray matter [GM]) and 1H- magnetization-prepared rapid gradient echo to assess GM atrophy (GM fraction). The mean disease duration was 3.1 years and the median Expanded Disability Status Scale score was 1 (range 0-4.5). Thirty-seven patients were classified as cognitively preserved and 21 as cognitively impaired. TSC was increased in GM and NAWM in cognitively impaired patients compared to cognitively preserved patients and healthy controls. Voxel-wise analysis demonstrated that sodium accumulation was mainly located in the neocortex in cognitively impaired patients. Regression analysis evidenced than the 2 best independent predictors of cognitive impairment were GM TSC and age. Receiver operating characteristic analyses demonstrated that sensitivity and specificity of the GM TSC to classify patients according to their cognitive status were 76% and 71%, respectively. This study provides 2 main findings. (1) In RRMS, total sodium accumulation in the GM is better associated with cognitive impairment than GM atrophy; and (2) total sodium accumulation in patients with cognitive impairment is mainly located in the neocortex.

Review and evaluation of a chiral enrichment model for chlordane enantiomers in the environment

Chlordane is an organochlorine pesticide that contains a mixture of components, some of which are chiral. Analysis of enantiomers can provide insights into the mechanisms of their sources, pathway, and fate. The objectives of this work were: (i) to review the published literature that reported chlordane enantiomer concentrations in various environmental compartments; (ii) to evaluate the applicability of a model developed by Hegeman and Laane (2002) for predicting the relative distribution of various chiral pesticides in the environment. This model predicts that enantiomer deviation increases in the following order: air, water, soil, molluscs, fish/birds, marine mammals, specific tissues, and enzymes; (iii) to determine the relative ranking of plants within the model. All data were converted into an enantiomer fraction and aggregated by environmental compartment using bootstrap averaging to compare to model predictions. Enantiomer distributions of cis-chlordane, trans-chlordane, oxychlordane, and heptachlor exo-epoxide were reported in soil, air, water/sediments, plants, and animals. Based on aggregated average estimates for enantiomer fraction, the deviation from racemic increased in the following order for cis-chlordane: water/sediments = lower trophic aquatic organisms < air < fish < soil < plants (all combined) < seal < polar bear < bird < whale; for trans-chlordane: fish < water/sediments < lower trophic aquatic organisms < air < soil < plants (all combined) < seal < whales < bird < polar bear; and for heptachlor exo-epoxide: plants (all combined) < fish < soil = whale < water/sediments < bird < air < seal < polar bear. Depending on the species used to represent marine mammals, the Spearman’s rank-order correlation coefficients of observed data against model predictions were + 0.75 or + 0.84 for cis-chlordane, + 0.41 or + 0.49 for trans-chlordane, and −0.59 or + 0.12 for heptachlor exo-epoxide. This suggests that the model is applicable for cis- and trans-chlordane, but not for heptachlor exo-epoxide. The fundamental mechanisms behind the observed enantiomeric enrichment are of eminent importance in understanding the enantioselective deviations.

A power free electrodialysis (PFED) for desalination

A power free electrodialysis (PFED) is proposed for water desalination by integrating with a reverse electrodialysis (RED) as an energy donor. The effects of flow rates, salt concentration ratio between high salt concentration compartment (HC) and low salt concentration compartment (LC) on energy generation are investigated. The combination of ED and RED for fresh water production is attempted and the desalination performances in both continuous and batch-wise modes are investigated. The results show that the integration is feasible and the conductivity of the product water can be as low as 72μS/cm, which is indubitably qualified for drinking. To test the robustness of this hybrid technology, the batch-wise mode is chosen to generate power from simulated seawater and wastewater. It is found that the PFED can be successfully carried with no significant desalination difference compared to NaCl solution. PFED is thus confirmed to be technically feasible, and economically attractive for water desalination without the consumption of external energy.

Influence of soil structure on the “Fv approach” applied to 238U and 226Ra

The soil-to-plant transfer factors were determined in a granitic area for the two long-lived uranium series radionuclides 238U and 226Ra. With the aim to identify a physical fraction of soil whose concentration correlates linearly with the plant concentration, the soil compartment was analyzed in various stages. An initial study identified the soil compartments as being either bulk soil or its labile fraction. The bulk soil was subsequently divided into three granulometric fractions consisting of: coarse sand, fine sand, and silt and clay. The soil-to-plant transfer of radionuclides for each of these three texture fractions was analyzed. Lastly, the labile fraction was extracted from each textural part, and the activity concentration of the radionuclides 238U and 226Ra was measured. In order to assess the influence of soil texture on the soil-to-plant transfer process, we sought to identify possible correlations between the activity concentration in the plant compartment and those found in the different fractions within each soil compartment. The results showed that the soil-to-plant transfer process for uranium and radium depends on soil grain size, where the results for uranium showed a linear relationship between the activity concentration of uranium in the plant and the fine soil fraction. In contrast, a linear relation between the activity concentration of radium in the plant and the soil coarse-sand fraction was observed. Additionally, the presence of phosphate and calcium in the soil of all of the compartments studied affected the soil-to-plant transfer of uranium and radium, respectively.

Differential Responses of Soybean and Sorghum Growth, Nitrogen Uptake, and Microbial Metabolism in the Rhizosphere to Cattle Manure Application: A Rhizobox Study.

In this study, we determined the capacity of soybean (Glycine max L. Merr. cv. Hoyoharuka) and sorghum (Sorghum bicolor L. Moench. cv. Hybrid Sorgo) to utilize different forms of nitrogen (N) in a rhizobox system. Seedlings were grown for 35 days without N or with 130 mg N kg-1 soil as ammonium sulfate or farmyard cattle manure. The soil fractions at different distances from the root were sliced millimeter by millimeter in the rhizobox system. We assessed the distribution of different forms of N and microbial metabolism in different soil fractions in the rhizosphere. There are no treatment-dependent changes in biomass production in the roots and shoots of soybeans, however, the ammonium and manure treatment yielded 1.30 and 1.40 times higher shoot biomass of sorghum than the control. Moreover, the depletion of inorganic N and total amino acids (TAA) in the rhizosphere was largely undetectable at various distances from the soybean roots regardless of the treatments employed. The addition of ammonium sulfate resulted in a decrease in the nitrate concentration gradient as the distance decreased from the sorghum roots. The addition of manure to the soil increased the N content in the sorghum shoots, 1.57 times higher than the control; this increase was negatively correlated with the concentrations of TAA in the soil of the root compartment. In addition, the application of manure simultaneously induced TAA depletion (i.e., the TAA concentration in root compartment was 1.48 times higher than that in bulk soil) and greater microbial activity and diversity in the sorghum rhizosphere, where higher microbial consumption of asparagine, glutamic acid, and phenylalanine were also observed near the roots. Our results are first to present the evidence that sorghum may possess a high capacity for taking up amino acids as a consequence of organic matter application, and microbial metabolism.

Bridging the Gap Between In Vitro Dissolution and the Time Course of Ibuprofen-Mediating Pain Relief

In vitro–in vivo extrapolation techniques combined with physiologically based pharmacokinetic models represent a feasible approach to establishing links between critical quality attributes and the time course of drug concentrations in vivo. By further integrating the results with pharmacodynamic (PD) models, scientists can also explore the time course of drug effect. The aim of this study was to assess whether differences in dissolution rates would affect the onset, magnitude, and duration of the time course of ibuprofen-mediating pain relief. An integrated in vitro–in vivo extrapolation–physiologically based pharmacokinetic/PD model was used to simulate pharmacokinetic and PD profiles for ibuprofen free acid (IBU-H) and its salts. Two elements of the pharmacokinetic profile, the peak of exposure (Cmax) and the time to peak concentration (Tmax), were sensitive to dissolution rate, whereas only 1 element of the pharmacodynamic profile was affected, namely the onset of drug action. The Cmax differences between IBU-H and its salts seem to be mitigated in the (hypothetical) effect compartment because of the concurrent distribution and elimination processes. Furthermore, the predicted maximum concentration in the effect compartment exceeded the EC80 value, which marks the plateau phase of the PD concentration–response curve, regardless of whether IBU-H or its salts were administered. Understanding the target site distribution kinetics and the potential nonlinearities between exposure and response will assist in setting criteria that are more scientifically based for the demonstration of therapeutic equivalence.

A New Mode of Reverse Electrodialysis Operation to Reduce Seawater RO Energy Demand

Introduction Water and energy are two of the main challenges facing our modern world today. With water shortages and pollution reaching alarming levels, research is pushed to look for alternative water sources, such as (secondary treated) waste water and seawater. In the case of seawater, the main issue is the large amount of energy needed for its desalination, around 2-3 kWh/m³ at a recovery of 50% (35 g/l total dissolved solids) in the case of state-of-the-art reverse osmosis (RO). By coupling RO with reverse electrodialysis (RED), the energy demand can be decreased in two ways: (1) energy can be produced in RED by the salinity gradient between the seawater and for example impaired water and (2) the concentration of the seawater decreases in RED, entailing a lower energy demand in the RO step. This type of hybrid can theoretically decrease the energy demand of seawater desalination to the point of energy neutrality and can even be energy producing [1,2]. However, the viability of the process is limited by the slow desalination kinetics in RED, resulting in a high required membrane area and consequent high capital costs. The desalination rate in RED is mainly limited in the first stages of desalination, where the low salinity compartment causes a high resistance of both the solution itself and of the membrane. Indeed it was shown that the membrane resistance mainly depends on the low salinity solution it is in contact with [3,4]. Figure 1. Envisioned hybrid (A)RED-RO process To overcome this initially high resistance, a new mode of RED operation was developed: assisted RED or ARED. Here, instead of producing energy, a small potential difference is applied in the same direction as the natural salt transport to increase the desalination rate. ARED can be incorporated into the hybrid system as shown in Figure 1. This study is one of the first to explore the possibilities of ARED on lab-scale. Materials and methods A 5-cell pair RED set-up was used for the ARED tests. Fujifilm type I and type II membranes were used, with an active membrane area of 7.8x11.2 cm². Spacers with a thickness of 485 μm were used to create the low and high salinity compartments. A constant current density (0-136 A/m²) was applied and the resulting voltage was recorded to create current-voltage curves. Experiments were executed in once-through mode to keep the influent concentrations constant. Results To study the influence of the low salinity compartment (impaired water compartment), the seawater compartment concentration was kept constant, at 0.5M NaCl, while the impaired water compartment concentration was varied (0.01, 0.05, 0.1 and 0.25M NaCl). All obtained current-voltage curves at the lower concentrations (0.01 and 0.05M NaCl) show a clear downward declination, indicating a significant decrease in resistance at increasing currents. At lower flow rates, this decrease in resistance becomes more apparent, as the residence time in the system increases. At higher concentrations (0.1 and 0.25M NaCl), the relation is linear, as theoretically expected. The observed decrease in system resistance is caused by an increase in concentration of the low salinity compartment due to the salt transport in the system. Galama et al. (2014) and Geise et al. (2014) showed that the low salinity compartment concentration determines the membrane resistance [3,4] and that an increase in the concentration of this compartment thus leads to a decrease in the membrane resistance as well. The rapid decrease in resistance observed in ARED is its main advantage. By incorporating it into the RED-RO hybrid, it increases the economic viability of the system. Further characterisation and modelling of the system is under way to further assess its value.

Growth Hormone Concentrations in Different Body Fluids Before and After Moderate Exercise.

BackgroundGrowth hormone (GH) has many direct and indirect actions and roles including substrate regulation and priming of some cells of the immune system, and the expected aspects of growth and repair. Different concentrations in human body fluids reflect the exercise-induced growth hormone response (EIGR) after exercise. In populations such as elite athletes, the invasive nature of venous sampling is poorly accepted. Thus, this study examines possible viable alternatives such as urine and saliva samples and the GH concentration.MethodsA heterogeneous group of 11 males (age 26.0 ± 5.0 years; body mass 76.5 ± 9.3 kg; VO2peak 57.0 ± 6.0 mL kg−1 min−1) ran for 40 min on a treadmill at 5 % below their individually indentified lactate threshold pace. Samples of urine, saliva and blood were collected immediately pre- and post-test and at 30 and 60 min post-test.ResultsSalivary GH was correlated with serum pre- and post-exercise (p < 0.001); urinary GH was correlated with serum (p < 0.05). However, despite being significantly correlated, it is clear from the large differences in absolute concentration in the three media that the appearance of serum GH due to exercise is different from that of the appearance of salivary and urinary GH. This aspect of compartmental exchanges is very difficult to define and to investigate. Differences in any analyte concentration in different compartments are to be expected between different media, and hence the same medium should be used where the same ‘pattern of response’ can be tracked.ConclusionsThe results suggest that urinary and saliva sampling cannot substitute for venous sampling with respect to exercise-induced changes in GH concentration. The use of the analyses in these three areas may be appropriate for further investigation.

A Review of Organophosphate Esters in the Environment from Biological Effects to Distribution and Fate.

Organophosphate esters (OPEs) are synthetic phosphoric acid derivatives used in a wide variety of applications including as flame retardants and plasticizers. Their production and usage has increased in recent years, due to the phase-out of other flame retardant formulations (e.g., polybrominated diphenyl ethers). As such, there has been a recent push to understand the global distribution of OPEs and their behaviour in biota. Multiple studies have been published over the last few years pertaining to OPE concentrations in biotic and abiotic environmental compartments, as well as the metabolism of OPEs in biota. This paper aims to provide a brief review of the occurrence and levels of OPEs in the environment, as well as recent developments concerning the elucidation of OPE metabolism in biota.

Subnuclear Localization of Human Topoisomerase I.

Human topoisomerase I is partitioned between the nucleolus and the nucleoplasm in the interphase cells. Under unstressed conditions it is concentrated in the first compartment but nucleolar concentration of the full length protein is lost after inactivation of relaxation activity. Due to the above, subnuclear localization of topoisomerase I is linked with DNA relaxation activity of topoisomerase I. Looking for other factors responsible for subnuclear distribution of topoisomerase I, we studied here localization of the fluorescently tagged fragments and point mutants of topoisomerase I in HeLa cells. We found that two regions of topoisomerase I, the N-terminal and the linker domains, were critical for subnuclear localization of the enzyme. The linker domain and the distal region of the N-terminal domain directed topoisomerase I to the nucleolus, whereas the remaining region of the N-terminal domain was responsible for the nucleoplasmic localization. The effects exhibited by the regions which contributed to nuclear distribution of topoisomerase I were independent of DNA relaxation activity. Localization mutations in both domains complemented one another giving the wild-type phenotype for the double mutant. These results suggest a two-stage model of regulation of partitioning of topoisomerase I between the nucleolus and the nucleoplasm. The first stage is a net of interactions provided by the N-terminal and the linker domains. The other stage, accessible only if the first net is balanced, is driven by DNA relaxation activity. J. Cell. Biochem. 118: 407-419, 2017. © 2016 Wiley Periodicals, Inc.

Mathematical models for drug diffusion through the compartments of blood and tissue medium

This paper is an attempt to establish the mathematical models to understand the distribution of drug administration in human body through oral and intravenous routes. Three models were formulated based on diffusion process using Fick’s principle and law of mass action. The rate constants governing the law of mass action were used on the basis of the drug efficacy at different interfaces. The Laplace transform and eigenvalue methods were used to obtain the solution of the ordinary differential equations concerning the rate of change of concentration in different compartments viz. blood and tissue medium. The drug concentration in the different compartments has been computed using numerical parameters. The graphs plotted illustrate the variation of drug concentration with respect to time using MATLAB software. It has been observed from the graphs that the drug concentration decreases in the first compartment and gradually increases in other compartments.

Differentiating two partial nitrification mechanisms: Inhibiting nitrite oxidizing bacteria activity or promoting ammonium oxidizing bacteria activity

Partial nitrification is usually more easily achieved for high NH4+ concentration wastewater. In this study, a two-compartment aerobic nitrification reactor was used to raise the NH4+ concentration in the first aerobic compartment and to enhance partial nitrification for low NH4+ concentration wastewater. In addition to the regular sludge wastage to maintain sludge retention time (SRT), extra sludge wastage was used to increase the specific biomass NH4+ load. The experimental results indicated that partial nitrification was closely associated to the specific biomass NH4+ load. The modelling results indicated that a low SRT was needed to maintain the low biomass concentration and high specific biomass NH4+ load. The increased AOB (ammonium oxidizing bacteria) activity, instead of the free ammonia (FA) inhibition of NOB (nitrite oxidizing bacteria) was identified to be the main mechanism for partial nitrification in low NH4+ concentration wastewater treatment with high specific biomass NH4+ load.

Predictive Modeling Applied to a Spent Fuel Dissolver Model—II: Uncertainty Quantification and Reduction

This work presents the application of the comprehensive predictive modeling methodology for single multiphysics time-dependent systems, developed by Cacuci and Ionescu-Bujor (2010), to a paradigm spent fuel dissolver model of interest to nonproliferation objectives, in order to quantify uncertainties due to dissolver model parameters and subsequently to combine all of the available experimental and computational information to obtain best-estimate values for model responses and parameters, along with reduced predicted uncertainties. This predictive modeling methodology uses the maximum entropy principle to construct an optimal approximation of the unknown a priori distribution for the a priori known mean values and uncertainties characterizing the model parameters and the computed and experimentally measured model responses. This approximate a priori distribution is subsequently combined using Bayes’ theorem with the likelihood provided by the multiphysics computational models. Finally, the posterior distribution is evaluated using the saddle-point method to obtain analytical expressions for the optimally predicted values for the parameters and responses of both multiphysics models, along with corresponding reduced uncertainties.The weighting functions used within this predictive modeling methodology are provided by the first-order sensitivities (i.e., functional derivatives) of the model’s response with respect to the model’s parameters. The dissolver model comprises 619 model parameters related to the model’s equation of state and inflow conditions. The sensitivities to all model parameters of the acid concentrations at each of these instances in time were computed exactly and efficiently in an accompanying work by Peltz and Cacuci (2015), using the adjoint sensitivity analysis method. These sensitivities are used in this work to quantify the uncertainties in the acid concentration (system responses) in various dissolver compartments, arising from uncertainties in the model parameters. Subsequently, the sensitivities are used within the predictive modeling methodology to combine the computational results with the available experiments, which were performed solely in the compartment farthest from the inlet. The results of applying the predictive modeling methodology yield optimally calibrated values for all 619 model parameters, with reduced predicted uncertainties, as well as optimal (best-estimate) predicted values for the acid concentrations, also with reduced predicted uncertainties. Notably, even though the experimental data pertain solely to the compartment farthest from the inlet (where the data were measured), the predictive modeling methodology actually improves the predictions and reduces the predicted uncertainties not only in the compartment in which the data were actually measured but also throughout the entire dissolver, including the compartment farthest from the measurements (i.e., at the inlet). This is because the predictive modeling methodology combines and transmits information simultaneously over the entire phase-space, comprising all time steps and spatial locations.The results obtained in this work establish confidence in the dissolver model’s accuracy for simulating the acid concentrations required to dissolve used nuclear fuel. In turn, these results will be used to generate source terms for key reprocessing facility components downstream and to support material accountability for nuclear safeguards.

Effects of air supply diffusers and air return grilles layout on contaminants concentration in bus passenger compartment

Ventilation system in a bus is employed to provide good indoor air quality and thermal comfort for passengers. Poor ventilation system will increase the concentration level of air contaminants which could affect the passenger’s health. The presence mixing ventilation system used in many buses is not efficient in removing the air contaminants from the passenger compartments. This article presents a study on the effects of using different ventilation setups on the concentration level of gases and particulate matters inside a passenger compartment of a university’s shuttle bus. The goal is to find a suitable layout of the air supply diffusers and air return grilles that would lower the concentration level of contaminants inside the passenger compartment. Field measurements were carried out to quantify the concentration of gases (carbon monoxide, carbon dioxide and formaldehyde) and particulate matters (PM1, PM2.5 and PM10). The measurements were done at the front section of the bus compartment, close to the front door. The data were acquired in the morning, afternoon and evening hours during a clear and sunny day. The bus travelled along an in-campus road with no passengers. A simplified three-dimensional model of the bus compartment was developed using computational fluid dynamics software. Flow analyses were carried out to predict distribution of gases and particulate matters concentration. The concentrations of carbon dioxide, carbon monoxide, formaldehyde and particulate matters obtained from the field measurements were used as boundary conditions and for validating the computational model. A parametric study was carried out to identify a suitable layout of air supply diffusers and air return grilles that would lower the concentration level of the air contaminants. Two types of ventilation systems were considered namely a displacement ventilation and an underfloor air distribution. Results show that the underfloor air distribution system is more effective in reducing the concentration level of gases and particulate matters inside the passenger compartment compared to the displacement ventilation system.

Subcellular compartmentation of sugars in wheat leaves under the influence of salinity and boron toxicity

ABSTRACTIn this study, long-term effects of salinity and high boron (B) on subcellular distribution of sugars in wheat leaves were investigated. Four treatments with three replications of each; control, high B, sodium chloride (NaCl) and NaCl + high B, respectively were established according to completely randomized design. Plants were grown hydroponically and harvested after 6 weeks onset of experiment. NaCl treatment markedly decreased the shoot fresh and dry weight compared to high B or NaCl + high Boron. It increased the sugar concentrations in subcellular compartments, whereas decreased in NaCl + high B. Contrary, NaCl either alone or in combination with high B decreased the sugar contents in whole leaf compared to control or high B. Overall, higher concentrations of sugars were observed in symplast compared to apoplast indicating the symplast as major compartment for sugar transport. Furthermore, wheat plants accumulate sugars in subcellular compartments to maintain their growth under stress conditions.