bluuebunny/crossref_metadata_2025 huggingface dataset:
Antioxidative Defense Enzymes in Placenta Protect Placenta and Fetus in Inherited Thrombophilia from Hydrogen Peroxide
Authors: Pristov Jelena Bogdanovic , Spasojevic Ivan , Mikovic Željko , Mandic Vesna , Cerovic Nikola , Spasic Mihajlo
Published: August 2010

Our aim was to investigate the activities of antioxidative defense enzymes in the placenta, fetal blood and amnion fluid in inherited thrombophilia. Thrombophilia was associated with nearly threefold increase of activity (p < 0.001) of the placental catalase (81.1 ± 20.6 U/mg of proteins in controls and 270.0 ± 69.9 U/mg in thrombophilic subjects), glutathione (GSH) peroxidase (C: 20.2 ± 10.1 U/mg; T: 60.0 ± 15.5 U/mg), and GSH reductase (C: 28.9 ± 5.6 U/mg; T: 72.7 ± 23.0 U/mg). The placental activities of superoxide dismutating enzymes—MnSOD and CuZnSOD, did not differ in controls and thrombophilia. Likewise, the activities of catalase and SOD in the fetal blood, and the level of ascorbyl radical which represents a marker of oxidative status of amniotic fluid, were similar in controls and thrombophilic subjects. From this we concluded that in thrombophilia, placental tissue is exposed to H2O2‐mediated oxidative stress, which could be initiated by pro‐thrombic conditions in maternal blood. Increased activity of placental H2O2‐removing enzymes protects fetus and mother during pregnancy, but may increase the risk of postpartum thrombosis.
Systemic Oxidative Stress Is Increased to a Greater Degree in Young, Obese Women Following Consumption of a High Fat Meal
Authors: Bloomer Richard J. , Fisher-Wellman Kelsey H.
Published: August 2010

High fat meals induce oxidative stress, which is associated with the pathogenesis of disease. Obese individuals have elevated resting biomarkers of oxidative stress compared to non‐obese. We compared blood oxidative stress biomarkers in obese (n = 14; 30 ± 2 years; BMI 35 ± 1 kg•m−2) and non‐obese (n = 16; 24 ± 2 years; BMI 23 ± 1 kg•m−2) women, in response to a high fat meal. Blood samples were collected pre‐meal (fasted), and at 1, 2, 4 and 6 hours post meal, and assayed for trolox equivalent antioxidant capacity (TEAC), xanthine oxidase activity (XO), hydrogen peroxide (H2O2), malondialdehyde (MDA), triglycerides (TAG), and glucose. An obesity status effect was noted for all variables (p < 0.001; MDA p = 0.05), with obese women having higher values than non‐obese, except for TEAC, for which values were lower. Time main effects were noted for all variables (p ≤ 0.01) except for TEAC and glucose, with XO, H2O2, MDA and TAG increasing following feeding with a peak response at the four or six hour post feeding time point. While values tended to decline by six hours post feeding in the non‐obese women (agreeing with previous studies), they were maintained (MDA) or continued to increase (XO, H2O2 and TAG) in the obese women. While no interaction effects were noted (p > 0.05), contrasts revealed greater values in obese compared to non‐obese women for XO, H2O2, MDA, TAG and glucose, and lower values for TEAC at times from 1–6 hours post feeding (p ≤ 0.03). We conclude that young, obese women experience a similar pattern of increase in blood oxidative stress biomarkers in response to a high fat meal, as compared to non‐obese women. However, the overall oxidative stress is greater in obese women, and values appear to remain elevated for longer periods of time post feeding. These data provide insight into another potential mechanism related to obesity‐mediated morbidity.
Metallothionein Induction Reduces Caspase‐3 Activity and Tnfα Levels with Preservation of Cognitive Function and Intact Hippocampal Neurons in Carmustine‐Treated Rats
Authors: Helal Gouda K. , Aleisa Abdulaziz M. , Helal Omayma K. , Al-Rejaie Salim S. , Al-Yahya Abdulaziz A. , Al-Majed Abdulhakeem A. , Al-Shabanah Othman A.
Published: August 2010

Hippocampal integrity is essential for cognitive functions. On the other hand, induction of metallothionein (MT) by ZnSO4 and its role in neuroprotection has been documented. The present study aimed to explore the effect of MT induction on carmustine (BCNU)‐induced hippocampal cognitive dysfunction in rats. A total of 60 male Wistar albino rats were randomly divided into four groups (15/group): The control group injected with single doses of normal saline (i.c.v) followed 24 h later by BCNU solvent (i.v). The second group administered ZnSO4 (0.1 µmol/10 µl normal saline, i.c.v, once) then BCNU solvent (i.v) after 24 h. Third group received BCNU (20 mg/kg, i.v, once) 24 h after injection with normal saline (i.c.v). Fourth group received a single dose of ZnSO4 (0.1 µmol/10 µl normal saline, i.c.v) then BCNU (20 mg/kg, i.v, once) after 24 h. The obtained data revealed that BCNU administration resulted in deterioration of learning and short‐term memory (STM), as measured by using radial arm water maze, accompanied with decreased hippocampal glutathione reductase (GR) activity and reduced glutathione (GSH) content. Also, BCNU administration increased serum tumor necrosis factor‐alpha (TNFα), hippocampal MT and malondialdehyde (MDA) contents as well as caspase‐3 activity in addition to histological alterations. ZnSO4 pretreatment counteracted BCNU‐induced inhibition of GR and depletion of GSH and resulted in significant reduction in the levels of MDA and TNFα as well as the activity of caspase‐3. The histological features were improved in hippocampus of rats treated with ZnSO4 + BCNU compared to only BCNU‐treated animals. In conclusion, MT induction halts BCNU‐induced hippocampal toxicity as it prevented GR inhibition and GSH depletion and counteracted the increased levels of TNFα, MDA and caspase‐3 activity with subsequent preservation of cognition.
Aging increases Oxidative Stress and Renal Expression of Oxidant and Antioxidant Enzymes that Are Associated with an Increased Trend in Systolic Blood Pressure
Authors: Gomes Pedro , Simão Sónia , Silva Elisabete , Pinto Vanda , Amaral João S. , Afonso Joana , Serrão Maria Paula , Pinho Maria João , Soares-da-Silva Patrício
Published: August 2010

The aim of this study was to investigate whether the effects of aging on oxidative stress markers and expression of major oxidant and antioxidant enzymes associate with impairment of renal function and increases in blood pressure. To explore this, we determined age‐associated changes in lipid peroxidation (urinary malondialdehyde), plasma and urinary hydrogen peroxide (H2O2) levels, as well as renal H2O2 production, and the expression of oxidant and antioxidant enzymes in young (13 weeks) and old (52 weeks) male Wistar Kyoto (WKY) rats. Urinary lipid peroxidation levels and H2O2 production by the renal cortex and medulla of old rats were higher than their young counterparts. This was accompanied by overexpression of NADPH oxidase components Nox4 and p22phox in the renal cortex of old rats. Similarly, expression of superoxide dismutase (SOD) isoforms 2 and 3 and catalase were increased in the renal cortex from old rats. Renal function parameters (creatinine clearance and fractional excretion of sodium), diastolic blood pressure and heart rate were not affected by aging, although slight increases in systolic blood pressure were observed during this 52‐week period. It is concluded that overexpression of renal Nox4 and p22phox and the increases in renal H2O2 levels in aged WKY does not associate with renal functional impairment or marked increases in blood pressure. It is hypothesized that lack of oxidative stress‐associated effects in aged WKY rats may result from increases in antioxidant defenses that counteract the damaging effects of H2O2.
Role of Creatine Supplementation on Exercise‐Induced Cardiovascular Function and Oxidative Stress
Authors: Kingsley Michael I. C. , Cunningham Daniel , Mason Laura , Kilduff Liam P. , McEneny Jane
Published: August 2010

Many degenerative diseases are associated with increased oxidative stress. Creatine has the potential to act as an indirect and direct antioxidant; however, limited data exist to evaluate the antioxidant capabilities of creatine supplementation within in vivo human systems. This study aimed to investigate the effects of oral creatine supplementation on markers of oxidative stress and antioxidant defenses following exhaustive cycling exercise. Following preliminary testing and two additional familiarization sessions, 18 active males repeated two exhaustive incremental cycling trials (T1 and T2) separated by exactly 7 days. The subjects were assigned, in a double‐blind manner, to receive either 20 g of creatine (Cr) or a placebo (P) for the 5 days preceding T2. Breath‐by‐breath respiratory data and heart rate were continually recorded throughout the exercise protocol and blood samples were obtained at rest (preexercise), at the end of exercise (postexercise), and the day following exercise (post24 h). Serum hypdroperoxide concentrations were elevated at postexercise by 17 ± 5% above preexercise values (p = 0.030). However, supplementation did not influence lipid peroxidation (serum hypdroperoxide concentrations), resistance of low density lipoprotein to oxidative stress (t1/2max LDL oxidation) and plasma concentrations of non‐enzymatic antioxidants (retinol, α‐carotene, β‐carotene, α‐tocopherol, γ‐tocopherol, lycopene and vitamin C). Heart rate and oxygen uptake responses to exercise were not affected by supplementation. These findings suggest that short‐term creatine supplementation does not enhance non‐enzymatic antioxidant defence or protect against lipid peroxidation induced by exhaustive cycling in healthy males.
The plant Extracts of Momordica Charantia and Trigonella Foenum Graecum Have Antioxidant and Anti‐Hyperglycemic Properties for Cardiac Tissue During Diabetes Mellitus
Authors: Tripathi Uma Nath , Chandra Deepak
Published: August 2010

Oxidative stress is currently suggested to play a major role in the development of diabetes mellitus. There is an increasing demand of natural anti‐diabetic agents, as continuous administration of existing drugs and insulin are associated with many side effects and toxicity. The present study was aimed to investigate the effect of Momordica charantia (MC) and Trigonella foenum graecum (TFG) extracts (aqueous) on antioxidant status and lipid peroxidation in heart tissue of normal and alloxan induced diabetic rats. In a 30 days treatment, rats were divided into six groups (I‐VI) of five animals in each, experiments were repeated thrice. Administration of MC (13.33 g pulp/kg body weight/day) and TFG (9 g seeds powder/kg body weight/day) extracts in diabetic rats has remarkably improved the elevated levels of fasting blood glucose. A significant decrease in lipid peroxidation (p<0.001) and significant increase in the activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione‐s‐transferase (GST) and reduced glutathione (GSH ) contents in heart tissue of diabetic rats were observed (group V and VI) upon MC and TFG treatment. Our studies demonstrate the anti‐hyperglycemic and anti‐oxidative potential of Momordica charantia and Trigonella foenum graecum, which could exert beneficial effects against the diabetes and associated free radicals complications in heart tissue.
Tumor Necrosis Factor‐α and Apoptosis Signal‐Regulating Kinase 1 Control Reactive Oxygen Species Release, Mitochondrial Autophagy and C‐Jun N‐Terminal Kinase/P38 Phosphorylation During Necrotizing Enterocolitis
Authors: Baregamian Naira , Song Jun , Bailey C. Eric , Papaconstantinou John , Evers B. Mark , Chung Dai H
Published: August 2010

Background: Oxidative stress and inflammation may contribute to the disruption of the protective gut barrier through various mechanisms; mitochondrial dysfunction resulting from inflammatory and oxidative injury may potentially be a significant source of apoptosis during necrotizing enterocolitis (NEC). Tumor necrosis factor (TNF)α is thought to generate reactive oxygen species (ROS) and activate the apoptosis signal‐regulating kinase 1 (ASK1)‐c‐Jun N‐terminal kinase (JNK)/p38 pathway. Hence, the focus of our study was to examine the effects of TNFα/ROs on mitochondrial function, ASK1‐JNK/p38 cascade activation in intestinal epithelial cells during NEC.

Results: We found (a) abundant tissue TNFα and ASK1 expression throughout all layers of the intestine in neonates with NEC, suggesting that TNFα/ASK1 may be a potential source (indicators) of intestinal injury in neonates with NEC; (b) TNFα‐induced rapid and transient activation of JNK/p38 apoptotic signaling in all cell lines suggests that this may be an important molecular characteristic of NEC; (c) TNFα‐induced rapid and transient ROs production in RIe‐1 cells indicates that mitochondria are the predominant source of ROS, demonstrated by significantly attenuated response in mitochondrial DNA‐depleted (RIE‐1‐ρ°) intestinal epithelial cells; (d) further studies with mitochondria‐targeted antioxidant PBN supported our hypothesis that effective mitochondrial ROS trapping is protective against TNFα/ROs‐induced intestinal epithelial cell injury; (e) TNFα induces significant mitochondrial dysfunction in intestinal epithelial cells, resulting in increased production of mtROS, drop in mitochondrial membrane potential (MMP) and decreased oxygen consumption; (f) although the significance of mitochondrial autophagy in NEC has not been unequivocally shown, our studies provide a strong preliminary indication that TNFα/ROs‐induced mitochondrial autophagy may play a role in NeC, and this process is a late phenomenon.

Methods: Paraffin‐embedded intestinal sections from neonates with NEC and non‐inflammatory condition of the gastrointestinal tract undergoing bowel resections were analyzed for TNFα and ASK1 expression. Rat (RIE‐1) and mitochondrial DNA‐depleted (RIE‐1‐ρ°) intestinal epithelial cells were used to determine the effects of TNFα on mitochondrial function.

Conclusions: Our findings suggest that TNFα induces significant mitochondrial dysfunction and activation of mitochondrial apoptotic responses, leading to intestinal epithelial cell apoptosis during NeC. Therapies directed against mitochondria/ROS may provide important therapeutic options, as well as ameliorate intestinal epithelial cell apoptosis during NeC.
γ‐Tocotrienol Prevents Oxidative Stress‐Induced Telomere Shortening in Human Fibroblasts Derived from Different Aged Individuals
Authors: Makpol Suzana , Abidin Azrina Zainal , Sairin Khalilah , Mazlan Musalmah , Top Gapor Md , Ngah Wan Zurinah Wan
Published: August 2010

The effects of palm γ‐tocotrienol (GGT) on oxidative stress‐induced cellular ageing was investigated in normal human skin fibroblast cell lines derived from different age groups; young (21‐year‐old, YF), middle (40‐year‐old, MF) and old (68‐year‐old, OF). Fibroblast cells were treated with γ‐tocotrienol for 24 hours before or after incubation with IC50 dose of H2O2 for 2 hours. Changes in cell viability, telomere length and telomerase activity were assessed using the MTS assay (Promega, USA), Southern blot analysis and telomere repeat amplification protocol respectively. Results showed that treatment with different concentrations of γ‐tocotrienol increased fibroblasts viability with optimum dose of 80 µM for YF and 40 µM for both MF and OF. At higher concentrations, γ‐tocotrienol treatment caused marked decrease in cell viability with IC50 value of 200 µM (YF), 300 µM (MF) and 100 µM (OF). Exposure to H2O2 decreased cell viability in dose dependent manner, shortened telomere length and reduced telomerase activity in all age groups. The IC50 of H2O2 was found to be; YF (700 µM), MF (400 µM) and OF (100 µM). Results showed that viability increased significantly (p < 0.05) when cells were treated with 80 µM and 40 µM γ‐tocotrienol prior or after H2O2‐induced oxidative stress in all age groups. In YF and OF, pretreatment with γ‐tocotrienol prevented shortening of telomere length and reduction in telomerase activity. In MF, telomerase activity increased while no changes in telomere length was observed. However, post‐treatment of γ‐tocotrienol did not exert any significant effects on telomere length and telomerase activity. Thus, these data suggest that γ‐tocotrienol protects against oxidative stress‐induced cellular ageing by modulating the telomere length possibly via telomerase.
Sustained Delivery of Nicotinamide Limits Cortical Injury and Improves Functional Recovery Following Traumatic Brain Injury
Authors: Goffus Andrea M. , Anderson Gail D. , Hoane Michael R.
Published: August 2010

Previously, we have demonstrated that nicotinamide (NAM), a neuroprotective soluble B‐group vitamin, improves recovery of function following traumatic brain injury (TBI). However, no prior studies have examined whether NAM is beneficial following continuous infusions over 7 days post‐TBI. The purpose of this study was to investigate the preclinical efficacy of NAM treatment as it might be delivered clinically; over several days by slow infusion. Rats were prepared with either unilateral controlled cortical impact (CCI) injuries or sham procedures and divided into three groups: CCI‐NAM, CCI‐vehicle and sham. Thirty minutes following CCI, Alzet osmotic mini‐pumps were implanted subcutaneously. NAM was delivered at a rate of 50 mg/kg/day for 7 days immediately post‐CCI. On day 7 following injury, the pumps were removed and blood draws were collected for serum NAM and nicotinamide adenine dinucleotide (NAD+) analyses. Starting on day 2 post‐CCI, animals were tested on a battery of sensorimotor tests (bilateral tactile adhesive removal, locomotor placing and limb‐use asymmetry). Continuous infusion of NAM resulted in a significant serum elevation in NAM, but not NAD+. Statistical analyses of the tactile removal and locomotor placing data revealed that continuous administration of NAM significantly reduced the initial magnitude of the injury deficit and improved overall recovery compared to the vehicle‐treated animals. NAM treatment also significantly decreased limb‐use asymmetries compared to vehicle‐treated animals. The overall extent of the cortical damage was also reduced by NAM treatment. No detrimental effects were seen following continuous infusion. The present results suggest that NAM delivered via a clinically relevant therapeutic regimen may truncate behavioral damage following TBI. Thus our results offer strong support for translation into the clinical population.
Role of Gender, Smoking Profile, Hypertension, and Diabetes on Saphenous Vein and Internal Mammary Artery Endothelial Relaxation in Patients with Coronary Artery Bypass Grafting
Authors: Muir Andrew Duncan , McKeown Pascal Patrick , Bayraktutan Ulvi
Published: August 2010

The aim of this study was to investigate if there was a link between the relaxant responses in saphenous vein (SV) and internal mammary artery (IMA) segments obtained from patients undergoing coronary artery bypass grafting and the patients′ cardiovascular risk factors. Endothelium‐(in)dependent relaxations were assessed by isometric tension studies. Endothelium‐dependent relaxant responses were greater in IMA than SV and gender, smoking profile and history of hypertension but not diabetes appeared to have an influence on these responses. Endothelium‐dependent relaxant responses in both IMA and SV were greater in males than females and relaxant responses in IMA segments were attenuated in smokers, whereas the opposite effect was noted in SV segments. Endothelium‐dependent relaxant responses in SV were lower in patients with hypertension. Endothelium‐independent relaxant responses were greater in IMA than SV. Endothelium‐independent responses were greater in male patients′ SV segments, but gender played no role in IMA segments. Diabetes had no effect on endothelium‐independent responses in IMA, but SV segments from diabetic patients had greater responses. Neither conduit′s endothelium‐independent response was affected by hypertensive status. The relationship between risk factor status and endothelial responses is multifactorial, with gender, hypertension, diabetes and smoking status all contributing.
Redox Homeostasis of Albumin in Relation to Alpha‐Lipoic Acid and Dihydrolipoic Acid
Authors: Atukeren Pinar , Aydin Seval , Uslu Ezel , Gumustas MKoray , Cakatay Ufuk
Published: August 2010

Albumin represents the predominant circulating antioxidant agent in plasma exposed to continuous oxidative stress and a change in serum albumin structure accounts for its antioxidant properties. Alterations in the redox status of albumin may result in impairments of its biological properties. Alpha‐lipoic acid (LA), a naturally occurring thiol compound found in virtually all species, is a potent antioxidant with high efficacy which is also involved in the chelation of metal ions, regeneration of antioxidants, and repair of oxidatively damaged proteins. In human body LA is rapidly reduced to dihydrolipoic acid (DHLA) after intake into the cell. Both, LA and DHLA are amphipathic molecules which act as antioxidants both in hydrophilic and lipophilic environments. The present study aimed to investigate the antioxidant/pro‐oxidant effects of LA and DHLA due to their concentrations in metal‐catalyzed protein oxidation (MCO) of human serum albumin (HSA). Progressive oxidative modification of albumin was found in MCO system by an increased content of protein hydroperoxides (POOH), protein carbonyl groups (PCO) which is the former′s major breakdown product, and other protein oxidation markers such as advanced oxidized protein products (AOPP) and protein thiol groups (P‐SH). The possible antioxidant protective effects of LA and DHLA were observed with 25 µM and 50 µM; DHLA being more influential. Protein oxidation parameters were found to be lower and P‐SH levels seemed higher. However, prooxidant effects of both LA and DHLA came on the scene with increased concentrations of 75 µM and 100 µM where the latter seemed the most hazardous with contradicted results. It is clear that the loss of biological activity of human serum albumin by MCO system appears of medical relevance and if LA exerts similar effects seen in the present study, it is possible that cellular prooxidant activity can also result consuming this unique antioxidant in certain doses.
Oxidative Stress and Autophagy in Cardiac Disease, Neurological Disorders, Aging and Cancer
Authors: Essick Eric E. , Sam Flora
Published: August 2010

Autophagy is a catalytic process of the bulk degradation of long‐lived cellular components, ultimately resulting in lysosomal digestion within mature cytoplasmic compartments known as autophagolysosomes. Autophagy serves many functions in the cell, including maintaining cellular homeostasis, a means of cell survival during stress (e.g., nutrient deprivation or starvation) or conversely as a mechanism for cell death. Increased reactive oxygen species (ROS) production and the resulting oxidative cell stress that occurs in many disease states has been shown to induce autophagy. The following review focuses on the roles that autophagy plays in response to the ROS generated in several diseases.
Potential Redox‐Sensitive Akt Activation by Dopamine Activates Bad and Promotes Cell Death in Melanocytes
Authors: Choi Hye-Ryung , Shin Jung-Won , Lee Hyun-Kyoung , Kim Jin-Young , Huh Chang-Hun , Youn Sang-Woong , Park Kyoung Chan
Published: August 2010

Dopamine (DA) is a well known oxidative neurotoxin. In addition, Akt has been reported to deliver a survival signal that inhibits apoptosis. However, it has also been reported that chronic Akt activation leads to apoptosis in response to oxidative stress. The objective of the present study was to investigate the possible role of the Akt pathway in vitiligo and its possible relationship with DA‐induced cell death using Mel‐Ab cells. Cultured Mel‐Ab cells were treated with DA with and without N‐Acetyl‐L‐cysteine (NAC), which is known to have antioxidative properties. Cell viability was then assessed by a crystal violet assay and Annexin staining was performed. The changes in the expression of Akt were analyzed by western blot analysis. The cell viability was reduced by approximately 60% in response to treatment with 500 µM DA, and NAC effectively prevented this cytotoxic effect. Likewise, treatment with DA produced numerous Annexin positive cells, while treatment with NAC prevented this apoptotic cell death. Akt was slowly phosphorylated after treatment with DA, while NAC clearly inhibited the DA‐induced Akt activation. Western blot analysis also showed that treatment with DA induced the activation of Bad. Finally, LY294002 exerted a protective effect against DA‐induced apoptotic cell death. DA may induce redox‐sensitive Akt activation and increase the level of Bad, which can promote cell death by heterodimerization with survival proteins. Moreover, NAC effectively protects against DA‐induced melanocyte death via inhibition of DA‐induced Akt activation.
Retrievals from GOMOS stellar occultation measurements using characterization of modeling errors
Authors: Sofieva V. F. , Vira J. , Kyrölä E. , Tamminen J. , Kan V. , Dalaudier F. , Hauchecorne A. , Bertaux J.-L. , Fussen D. , Vanhellemont F. , Barrot G. , Fanton d'Andon O.
Published: August 2010

Abstract. In this paper, we discuss the development of the inversion algorithm for the GOMOS (Global Ozone Monitoring by Occultation of Star) instrument on board the Envisat satellite. The proposed algorithm takes accurately into account the wavelength-dependent modeling errors, which are mainly due to the incomplete scintillation correction in the stratosphere. The special attention is paid to numerical efficiency of the algorithm. The developed method is tested on a large data set and its advantages are demonstrated. Its main advantage is a proper characterization of the uncertainties of the retrieved profiles of atmospheric constituents, which is of high importance for data assimilation, trend analyses and validation.
Magnetic field structure of large-scale plasmoid generated by the fast reconnection mechanism in a sheared current sheet
Authors: Ugai M.
Published: August 2010

Abstract. On the basis of the spontaneous fast reconnection model, three-dimensional magnetic field profiles associated with a large-scale plasmoid propagating along the antiparallel magnetic fields are studied in the general sheared current sheet system. The plasmoid is generated ahead of the fast reconnection jet as a result of distinct compression of the magnetized plasma. Inside the plasmoid, the sheared (east-west) field component has the peak value at the plasmoid center located at x=XC, where the north-south field component changes its sign. The plasmoid center corresponds to the so-called contact discontinuity that bounds the reconnected field lines in xXC. Hence, contray to the conventional prediction, the reconnected sheared field lines in xXC. It is demonstrated that the resulting profiles of magnetic field components inside the plasmoid are, in principle, consistent with satellite observations. In the ambient magnetic field region outside the plasmoid too, the magnetic field profiles are in good agreement with the well-known observations of traveling compression regions (TCRs).
Stage level, volume, and time-frequency information content of Lake Tana using stochastic and wavelet analysis methods
Authors: Chebud Y. , Melesse A.
Published: August 2010

Abstract. Lake Tana is the largest fresh water body situated in the north western highlands of Ethiopia. It serves for local transport, electric power generation, fishing, ecological restoration, recreational purposes, and dry season irrigation supply. Evidence show, the lake has dried at least once at about 15 000–17 000 BP (before present) due to a combination of high evaporation and low precipitation events. Past attempts to observe historical fluctuation of Lake Tana based on simplistic water balance approach of inflow, out-flow and storage have failed to capture well known events of drawdown and rise of the lake that have happened in the last 44 years. This study is aimed at simulating the lake level, specifically extreme events of the lake variation using stochastic approaches. Fourty-four years of daily, monthly and mean annual lake level data has showed a Gaussian variation with goodness of fit at 0.01 significant levels of the Konglomorov-Simrnov test. Three stochastic methods were employed, namely perturbations approach, Monte-Carlo methods and wavelet analysis, and the results were compared with the stage level measurements. The stochastic simulations predicted the lake stage level of the 1972, 1984 and 2002/2003 historical droughts 99% of the time. The information content (frequency) of fluctuation of Lake Tana for various periods was resolved using Wigner's Time-Frequency Decomposition method. The wavelet analysis agreed with the perturbations and Monte Carlo simulations resolving the time (1970s, 1980s and 2000s) in which low frequency and high spectral power fluctuation has occurred. In summary, the Monte-Carlo and perturbations methods have shown their superiority for risk analysis over deterministic methods while wavelet analysis has met reconstructing stage level historical record at multiple time scales. A further study is recommended on dynamic forecasting of the Lake Tana stage level using a combined approach of the perturbation and wavelet analysis methods.
Evaporation of the Ethanol and Water Components Comprising a Binary Liquid Mixture
Authors: O'Hare K. D. , Spedding P. L. , Grimshaw J.
Published: August 2010

Evaporation studies were conducted on the ethanol‐water system. The evaporation rates of the ethanol and water components were determined experimentally, over a range of compositions. The rate of change in the composition of the evaporating mixture was monitored, and the effect of concentration on the ethanol component evaporation rate (per unit mass of ethanol remaining) was investigated. Preferential adsorption of alcohol on the interface in low ethanol concentration solutions allowed ethanol to evaporate more rapidly in these solutions.
Effectiveness Factors in Anaerobic Biofilms: A Pseudoanalytical Equation for Parallel and Consecutive Reactions
Authors: Escalera C. R. , Maezawa A. , Uchida S. , Kuroda M.
Published: August 2010

The effectiveness factors for an anaerobic biofilm in which a parallel‐consecutive reaction occurs were studied theoretically. A pseudo‐analytical equation to represent the effectiveness factors (Efj) was developed as a function of a dimensionless parameter called the overall biofilm property value (MOj, and dimensionless concentrations at the surface of the biofilm (Bj). The parameter Moj is a combination of the individual biofilm property values (Mj) which represent biofilm characteristics. The applicability of these approximation equations is demonstrated experimentally for the degradation of a mixture of volatile fatty acids in which acetic acid is predominant. As the decompositions of these acids are considered to be rate‐limiting in anaerobic biofilm processes, this approximation equation may be used for the design and/or performance evaluation of biofilm reactors.
Electrochemical Methods for the Treatment of Industrial Process Streams and Effluents: Part I: Cell Design and the Recovery of Dissolved Metals by Electrodeposition
Authors: Scott K.
Published: August 2010

The use of electrochemical techniques is increasing rapidly for the treatment of a wide range of industrial effluents and process streams. This review considers these applications, for both liquid‐based and gas‐based streams, including the removal and recovery of dissolved metals, the destruction of dissolved organics, and the treatment of flue gases. Membrane‐based electrochemical methods such as electrodialysis are also discussed. Many of the methods described are used commercially, whilst many more are only at the prototype stage. The growing importance of electrochemical technology in this area is made evident by this review. Part I reviews the applications of electrochemistry and the cell designs for the recovery of metals by electrodeposition. This includes the use of two‐dimensional and three‐dimensional electrodes for recovery of precious metals and heavy metals. Part II reviews methods for waste‐gas treatment, organic chemical disposal and membrane‐based techniques.
Electrochemical Methods for the Treatment of Industrial Process Streams and Effluents: Part II: Electrochemical‐Based Methods for the Treatment of Flue Gases, and Aqueous Streams Containing Organic and Inorganic Chemicals
Authors: Scott K.
Published: August 2010

The second part of this review considers electrochemical methods for the treatment of organic and inorganic species, the treatment of flue gases and waste gases, and membrane‐based electrochemical techniques. These methods include both direct and indirect oxidation and reduction methods for toxic organics and cyanides. Membrane‐based methods include electrodialysis, electro‐osmosis and electrophoresis. Other aspects considered are electrosorption, electrochemical ion‐exchange, electroflotation, and electrochemically‐enhanced ultrafiltation.
The Freeze Concentration Process and its Applications
Authors: Englezos P.
Published: August 2010

In this paper, the freeze concentration separation process is described and the status of its industrial applications is reviewed. The pilot plant and commercial applications in the chemical and food processing industry for desalination and environmental protection, and in the pulp and paper industry are summarized. The advantages of using this process in the various industrial sectors as well as the limitations are delineated. The development of the clathrate hydrate process is also discussed. Finally, some anticipated developments are described.
Determining Optimum Column Height in Direct‐Contact Heat Transfer Columns
Authors: Lench M.J. , Worthington H.
Published: August 2010

A potential use for direct‐contact heat transfer in a cooling crystalliser has led to this investigation of a countercurrent direct‐contact heat transfer system. A computer‐based incremental model for predicating column height has been developed as a design tool. Certain simplifying assumptions are incorportated into the model, which gives agreement with experimental data to within the experimental error of 20%.
Production of Crotonaldehyde from Acetaldol
Authors: Atalay S. , Atalay F. S.
Published: August 2010

Optimum operating conditions for the production of crotonaldehyde from acetaldol were investigated and the kinetics of the reaction were determined. The most important operating conditions were found to be the cracking time, the pH value of the reaction mixture, and the initial concentration of acetaldol. The order of the reaction was found to be 1.8 with respect to the acetaldol concentration. The kinetic parameters were determined to be 20.583 (m3/kmol)0.8/min for the frequency factor, and 3416.800 kJ/kmol for the activation energy.
Alumina‐Ceramic Microfiltration Membranes: Preparation, Characterization and Some Properties
Authors: Mikuláŝek P. , Doleček P. , Šedá H. , Cakl J.
Published: August 2010

The thin‐layer ceramic membranes have a chemistry and morphology that are different from polymeric membranes. These differences expand the application of membranes into environments where current polymeric membranes fail, and require an evaluation of the characterization and performance parameters.

The conventional method that was adapted for the preparation of microfiltration alumina membranes is described. The use of a liquid displacement (modified bubble‐point) method to characterize tubular membrane microfilters in terms of pore sizes and pore size distributions is presented. The flux performance of supported alumina membranes is also described. The pore size distribution of tubular filters and flow of liquid through the membranes are discussed. Experimental results for different alumina microfilters are presented.

The characterization studies reported in this paper are applicable to other ceramic membranes and represent a significant advance in the understanding of the performance of ceramic membranes in various applications.
An Adaptive Bilinear Model‐Predictive Control Algorithm for a Plate Heat Exchanger
Authors: Al‐zahrani A. A. , Wali M. M. Noor
Published: August 2010

An adaptive bilinear model‐predictive controller having a single tuning parameter, was used to control the temperature for a plate heat exchanger simulation. The parameters of the bilinear model are estimated at each sampling instant via a recursive least‐square method with a variable forgetting factor. The model and the control algorithm are updated accordingly. An algorithm for elimination of steady‐state offset was also implemented.

The controller performance was tested for various changes in load and setpoint. It was found that adaptation eliminates the need for a filter. The controller performance was found to be excellent when the steady‐state offset compensator algorithm was implemented.
Removal of 230Th and other Metals from Sulphuric Acid Leach Uranium Mill Solution by Solvent Extraction, Adsorption and Precipitation
Authors: Nirdosh I. , Vogl A. K. , Carroll S. M.
Published: August 2010

230Th and other metals were removed from the Key Lake (Saskatchewan) uranium mill leach solution by three methods. First, solvent extraction with D2EHPA, TBP and Primene JMT in kerosene diluent. Second, by adsorption on MnO2 and clays. Third, using metal hydroxides after they were precipitated out from the leach solution. It was found that complete removal was possible with either 5 vol% Primene JMT (plus 5 vol% iso‐decanol) in 90 vol% kerosene, or by adsorption onto clays, or with hydroxides precipitated at pH > 2.4. Both 230Th and 226Ra adsorption on clay conformed to the Freundlich isotherm.
Dissolution of Potash Ore in Solutions of High Sodium Chloride Concentration
Authors: Gillies R.G. , Madge D.N. , Shook C.A.
Published: August 2010

An experimental investigation of the dissolution of KCI‐containing ore in brines of high NaCl content has been conducted. The dissolving surface was vertical and motion of the solution was due only to free convection. The effects of ore composition and brine NaCl concentration were studied for unsaturated brines using both reconstituted ore and raw ore slabs (11.5 cm high). These dissolution rates were consistent with previous free convection heat and mass transfer results, when the interfacial solution was assumed to be saturated with respect to both KCl and NaCl (the invariant point composition).

Dissolution by brines saturated with respect to NaCl was investigated with respect to the effects of crystal size in the slabs, solution KCl concentration, temperature and time. Dissolution rates were much lower in these cases and appeared to be controlled by a surface reaction. The mechanism of dissolution appears to involve penetration of the slab by the dissolving solution.
Correlation of Mass Transfer Coefficient in Stratified Gas‐Liquid Two‐Phase Flow in a Horizontal Rectangular Duct
Authors: Tomida T. , Suekuni N.
Published: August 2010

Liquid‐side mass transfer coefficients were determined using a horizontal rectangular duct (3cm x 3cm and 4m length) with carbon dioxide desorbing from water and from aqueous solutions of malt syrup. Simultaneously, measurements were made of the parameters characterizing the liquid film flow such as the liquid film thickness and surface velocity. Experiments were mainly conducted within the range of stratified gas‐liquid two‐phase flow. Based on the analogy between mass and momentum transfer at the liquid film surface, the experimental data for the liquid‐side mass transfer coefficient were correlated with the liquid‐film flow velocity. In order to estimate the parameters of film flow, a correlation for the average film thickness was obtained, and the surface velocity was represented graphically as a function of the gas velocity, slip velocity and superficial liquid Reynolds number.
Prediction of Holdup in Pipe Two‐phase Gas‐Liquid Co‐current Down Flow at −45d̀
Authors: Spedding P.L. , Mcbride W.J.
Published: August 2010

Holdup was measured for air‐water co‐current two‐phase flow in a perspex tube (45.4 mm id) set at an angle of −45d̀. The data were used to check the predictions of holdup given by various models (>120) using the input and geometrical conditions of the experiments. The prediction data were grouped according to the flow regimes that were observed for the system. Four models gave acceptable predictions for the annular‐plus‐wave condition, two of the models were also successful in predicting the annular‐plus‐droplet regime. Ten models were successful with droplet flow, and four models with the slug‐plus‐froth regime. No model could predict successfully for either the stratified or slug‐type flow regimes. In general, prediction performance deteriorated as the downward angle of inclination increased from the horizontal position.
Modification of Particles Using Silane and Methane in a Plasma‐Jet Fluidized Bed Reactor
Authors: Uemiya S. , Hanabusa T. , Kojima T.
Published: August 2010

Modification of alumina and carbon particles using silane and methane was carried out in a D.C. plasma‐jet fluidized bed reactor at atmospheric pressure. XRD, SEM and EPMA results showed that b‐SiC was formed inside and on the surface of the carbon particles. For the alumina particles, metallic Si was deposited inside and on the surface of the particles, but unfortunately the X‐ray reflection peak of b‐SiC was difficult to observe due to interference by the alumina peak. Speculations are offered concerning the mechanism of the deposition inside and on the surface of the particles.
Review of Real Time Optimization in the Chemical Process Industries
Authors: Naysmith M. R. , Douglas P. L.
Published: August 2010

Real Time Optimization (RTO), or On‐Line Optimization, is the continuous reevaluation and alteration of operating conditions of a process so that the economic productivity of the process is maximized subject to operational constraints. The purpose of this paper is to review the available literature in the area of real time optimization, with particular attention to the methodologies being used at present. The general components which make up a real time optimizer, the process model, objective function, optimization algorithm, data reconciliation and gross error detection, are also reviewed. Finally implementation of real time optimizers is covered including user interfacing and on‐going maintenance of the system.
Use of Fluidized Bed for Intensification of Microfiltration on Ceramic Membranes
Authors: Mikulášek P. , Filandrová L.
Published: August 2010

The influence of a fluidized bed on permeate flux during the microfiltration of model dispersions by ceramic membranes has been studied Following description of the basic characteristic of alumina tubular membranes, model dispersions and the spherical particles used, some comments about the experimental system and experimental results for different microfiltration systems are presented From analysis of the experimental results it is concluded that the use of a fluidized bed resulted in a significant increase in permeate flux when compared with results obtained in an empty tube system. This phenomenon is especially pronounced during the microfiltration of polymeric dispersion when the permeate flux in a fluidized bed system was nearly five times higher. It was found that the optimum porosity was approximately 0.8 for a fluidized bed exhibiting maximal values of permeate flux.
Investigation of Flux in Flat‐Plate Modules for Membrane Distillation
Authors: Burgoyne A. , Vahdati M.M. , Priestman G.H.
Published: August 2010

A theoretical model for predicting the behaviour of membrane distillation by incorporating mass and heat transfer equations has been used to find permeate fluxes, and has been validated experimentally. The model accurately predicts mass and heat transfer. The main work studied the effect of module design using a flat‐plate module in laminar flow conditions. Areas of investigation included the use of channels across the membrane surface, decreasing the available membrane surface area, and widening the inlet and outlet channels. The work showed that widening the channels increased the flux. Increased flux was also obtained by the use of channels on the permeate side, though not on the feed side.
Kinetics Studies on Effect of Recycled Water on Flotation of Copper Tailings from Benambra Mines, Victoria
Authors: Haran N. P. , Boyapati E. R. , Boontanjai C. , Swaminathan C.
Published: August 2010

Batch rougher flotation study was conducted on copper tailings from Benambra to compare flotation kinetics at optimised condition, using Melbourne, mine, dewnised and recycled waters. The results showed an enhanced copper grade and recovery when deionised water was used as compared to when Melbourne, mine or recycled waters were used, the greaterflotation rate was due to the near absence of dissolved organic and inorganic species. Fresh mine water gave better copper grade and recovery and an enhanced flotation rate as compared to Melbourne water. Improved flotation kinetics in first recycling of Melbourne and deionised waters were observed. Three recycles of mine water in the flotation process indicated a steady‐state rate for copper tailings. This was not valid for Melbourne and deionised waters where flotation was inhibited successively by three water‐recycles. Organic species such as thio‐phosphates and carbamates released from residual reagents in water, and inorganic speciesfrom the tailing sample that dissolves, are responsible for altering water quality and hence the flotation kinetics.
Nonlinear Driving Force Approximations of Intraparticle Mass Transfer in Adsorption Processes: The Effect of Pellet Shape
Authors: Georgiou A. , Kupiec K.
Published: August 2010

A general nonlinear driving force (NLDF) approximation of adsorbate uptake rate in terms of pellet geometry is presented. The results show that the accuracy of the proposed NLDF model is very good over the entire time (fractional uptake) domain, significantly improving over both the Linear Driving Force (LDF) and the Quadratic Driving Force (QDF) models.
Holdup Prediction in Vertical Upwards to Downwards Flow
Authors: Spedding P. L.
Published: August 2010

Tests of holdup prediction models have shown that horizontal/vertical flow conditions in general gave different performance than downward flow conditions. For horizontal/vertical flow the slug/bubble regimes were handled by the Nicklin [22] model; the annular regimes by the Spedding‐Spence [42] and Spedding‐Chen II [27] models; the droplet and film‐plus‐droplet regimes by the Taitel‐Dukler [48] model; the stratified‐blow‐through‐slug regime by the Hughmark [14] and Turner‐Wallis [49] models; the annular‐blow‐through‐slug regime by the Lockhart‐Martinelli [19], Chen [7], Spedding‐Chen [27], Spedding‐Spence [42], Nishino [23] and Gregory‐Scott [13] models. Stratified flows could not be handled completely by any model although the Kawaji [17] and Spedding‐Hand [29] and Hart [16] models handled horizontal flow. For downward inclinations the annular‐plus‐droplet and droplet regimes were handled by the Chen [7], Spedding‐Chen II [27], Taitel‐Dukler [48] and Spedding‐Hand [29] models. Other regimes were not handled by any one model, highlighting the need for development of new models based on a particular understanding of flow in the region of downward flow.
Membrane‐Based Gas Separation: Potential Energy Recovery and Greenhouse Abatement Applications
Authors: Da J. C. D. , Lu G. Q. , Rudolph V.
Published: August 2010

Diversification of energy supply is generally regarded as desirable, particularly if directed to renewable energy and greenhouse benign technologies. Various opportunities are becoming available for the application of memebrane‐based gas separations, particularly for upgrading landfill gas. Although the trade‐off between permeability and selectivity is an inherent conflict of priorities for the design of membranes, research and development efforts have focused on selecting materials and developing synthesis processes to improve both selectivity and permeability. This paper considers the use of landfill gas as a significant global renewable resource, and the various methane (CH4) purification technologies. The development of materials to enhance membrane‐based gas separations is also discussed.