An air-cathode MFC-adsorption hybrid system, made from earthen pot was designed and tested for simultaneous wastewater treatment and energy recovery. Such design had demonstrated superior characteristics of low internal resistance (29.3Ω) and favor to low-cost, efficient wastewater treatment and power generation (55mW/m(3)) with average current of 2.13±0.4mA. The performance between MFC-adsorption hybrid system was compared to the standalone adsorption system and results had demonstrated great pollutants removals of the integrated system especially for chemical oxygen demand (COD), biochemical oxygen demand (BOD3), total organic carbon (TOC), total volatile solids (TVS), ammoniacal nitrogen (NH3-N) and total nitrogen (TN) because such system combines the advantages of each individual unit. Besides the typical biological and electrochemical processes that happened in an MFC system, an additional physicochemical process from the activated carbon took place simultaneously in the MFC-adsorption hybrid system which would further improved on the wastewater quality.
Individual septic tanks are the most common means of on-site sanitation in Malaysia, but they result in a significant volume of septage. A two-staged vertical flow constructed wetlands (VFCWs) system for the treatment of septage was constructed and studied in Sarawak, Malaysia. Raw septage was treated in the first stage wetlands, and the resulting percolate was fed onto the second stage wetlands for further treatment. Here, the effects of a batch loading regime on the contaminant removal efficiency at the second stage wetlands, which included palm kernel shell within their filter substrate, are presented. The batch loading regime with pond:rest (P:R) period of 1:1, 2:2 and 3:3 (day:day) was studied. The improvement of the effluent redox condition was evident with P:R = 3:3, resulting in excellent organic matters (chemical oxygen demand and biochemical oxygen demand) and nitrogen reduction. The bed operated with P:R = 1:1 experienced constant clogging, with a water layer observed on the bed surface. For the P:R = 3:3 regime, the dissolved oxygen profile was not found to decay drastically after 24 hours of ponding, suggesting that the biodegradation mainly occurred during the first day. The study results indicate that a suitable application regime with an adequate rest period is important in VFCWs to ensure efficient operation.
The electronic absorption spectra of eight substituted acetic acids have been measured at room temperature in several solvents. The ground state dipole moments are evaluated experimentally for these molecules. These ground state values are used in conjunction with the spectral results to evaluate their first electronically excited state dipole moments. For all the molecules investigated here the dipole moments in the excited state are higher than their ground state values.
Summary: Home oxygen therapy programme is new in Malaysia. This programme enables children with respiratory insufficiency to be discharged home early.
Materials and Methods: Long term oxygen therapy was initiated using an oxygen concentrator in patients who i) remained hypoxic while breathing room air, ii) experienced desaturations of more than 20% during sleep as seen in patients with severe laryngomalacia and obstructive sleep apnoea syndrome and iii) had pulmonary hypertension with or without polycythemia. The median with first and third quartile values are presented for the quantitative variables.
Results: A total of 71 patients mainly children with bronchopulmonary dysplasia (BPD) (32) and bronchiolitis obliterans (12) were discharged home on this programme. The median age at which home oxygen was initiated in children with BPD was 5.0 (Q1:2 Q3:8) months. The median total duration of oxygen requirement for BPD was 8.0 (Q1:5, Q3:12) months. The median duration of home oxygen dependency was 3.5 (Q1:3, Q3:6) months. However children with bronchiolitis obliterans required longer duration of oxygen therapy compared to children with BPD i.e. median duration of 28 months (Q1:14.5 Q3:66). In other respiratory conditions the mean duration of supplemental oxygen varies some of which may be life long.
Conclusions: This paper has shown the importance of home oxygen program in children with respiratory disorders. It has significantly shortened hospital stay and thus saves hospital costs and prevents prolonged separation from the family.
Oxygen consumption values calculated by Fick's principle (cVO2) were compared to simultaneously obtained values measured by indirect calorimetry (mVO2) in two groups of patients; post-coronary artery bypass graft (post-CABG) and septic shock. In both groups of patients, oxygen consumption values derived using indirect calorimetry were higher than that from Fick's principle. Whilst the bias obtained between the two methods of measurement were of acceptable amount clinically, the limits of agreement were wide: -57 to 51 ml.min-1.m-2 in the post-CABG group and -101 to 67 ml.min-1.m-2 in the group of septic patients; indicating that significant differences exist between paired individual values such that cVO2 and mVO2 were not interchangeable in this study.
Hypoxic cells in tumors are proposed to consist of at least 2 types, depending on whether they remain hypoxic for long (chronic hypoxia) or short (acute hypoxia) periods. Experimental evidence of the possible presence ofacutely-hypoxic cells in one type of murine tumour is presented. Finally, the possible implications for radiotherapy and chemotherapy of the presence of acutely-hypoxic cells in human tumors is discussed briefly.
Effective treatment of wastewater is crucial in order to achieve a sustainable development. For instance, highly efficient treatment processes with low capital requirements are the major prerequisite for implementation of the advanced wastewater treatment operations. Among various available treatment methods, the application of coagulation-flocculation process by using natural coagulant; chitosan has vast advantages such as low operating cost, environmental friendly and highly effective in the wastewater treatment operations. The application of nanotechnology in numerous treatment techniques are considered as the most significant advances in water and wastewater treatment practices. The utilization of magnesium oxide (MgO) as nano-adsorbent has recently gained attention as a potential treatment method in water remediation particularly for treating effluents with high amount of organic dyes and heavy metals due to its high treatment efficiency, low cost, versatility and environment compatibility. The purpose of this study was to determine the effectiveness of coagulation-flocculation process when using novel coagulant in which MgO coated with chitosan by investigating the percentage removal of several significant parameters which were turbidity, chemical oxygen demand (COD) and suspended solid. The removal efficiencies were determined throughout a series of experiments carried out using a standard jar test procedure in which three different coagulants; chitosan, MgO coated with chitosan and MgO were tested on water samples taken from Sg. Pusu. In addition, a set of experiments was designed using response surface methodology (RSM) in order to optimize adsorption of chitosan into MgO. The experiments were conducted at various concentrations of chitosan (10-30 mg/ml) and selected MgO dosage ranges (10-30 mg). From the obtained results, it was found that chitosan-MgO coagulant has good removal efficiencies of turbidity, chemical oxygen demand (COD) and suspended solids at 92%, 91%, and 98% respectively from the optimization of adsorption of chitosan-MgO. The MgO coated with chitosan is the best coagulant in this study compared to chitosan and MgO alone because of the ability of treating the river water with up to 90 % removal for all the main parameters. The results showed that coagulation-flocculation is effective as a treatment for treating river water.
The refining of the crude palm oil (CPO) generates the palm oil refinery effluent (PORE). The presence of high contents of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, and suspended solids (SS) in PORE encourages the determination of an effective treatment process to minimize the environmental pollution and preserve aquatic life. In the present study, a biodegradable natural polymer, namely tannin, was utilized as a coagulant to treat PORE. The coagulation experiment was conducted using a jar test apparatus. The tannin coagulation efficiency was evaluated based on the BOD, COD, turbidity, and SS removal from PORE by varying the tannin dose (50-300 mg/L), pH (pH 4-10), treatment time (15-90 min), and sedimentation time (15-90 min). It was found that the maximum removal of BOD, COD, turbidity, and SS was 97.62%, 88.89%, 93.01%, and 90.21%, respectively, at pH 6, a tannin dose of 200 mg/L, 60 min of coagulation time, and 60 min of sedimentation time. Analyses of isotherm models revealed that the Freundlich isotherm model was well fitted with the coagulation study. Kinetics studies show that the pseudo-second-order kinetics model was the well-fitted kinetics model for the BOD, COD, turbidity, and SS removal from PORE using tannin as a polymeric coagulant. The determination of thermodynamics parameters analyses revealed that BOD, COD, turbidity, and SS removal from PORE was spontaneous, exothermic, and chemical in nature. The finding of the present study shows that tannin as a natural polymeric coagulant would be utilized in PORE treatment to avoid toxic sludge generation.
This study tested the oxygen consumption rates (OCR), energy, and thermal coefficient of juvenile Lutjanus malabaricus (60 fish, size: 4.53 ± 1.14 g) at four temperatures of 22, 26, 30 and 34 °C. During 30 days of experimental period 5 fish tank-1 were reared at four temperatures with three replicates in intermittent flow respirometers in a recirculatory system under laboratory conditions. As expected, oxygen consumption rates increased significantly (P
Many wastewater treatment plants (WWTPs) operating in biological nitrogen removal activated sludge process in the tropics are facing the pressure of increasingly stringent effluent standards while seeking solutions to reduce the plants' energy consumption and operating cost. This study investigated the feasibility of applying low-dissolved oxygen (low-DO) nitrification and utilizing slowly-biodegradable chemical oxygen demand (sbCOD) for denitrification, which helps to reduce energy usage and operating cost in treating low soluble COD-to-nitrogen tropical wastewater. The tropical wastewater was first characterized using wastewater fractionation and respirometry batch tests. Then, a lab-scale sequencing batch reactor (SBR) was operated to evaluate the long-term stability of low-DO nitrification and utilizing sbCOD for denitrification in an anoxic-oxic (AO) process treating tropical wastewater. The wastewater fractionation experiment revealed that particulate settleable solids (PSS) in the wastewater provided slowly-biodegradable COD (sbCOD), which made up the major part (51 ± 10%) of the total COD. The PSS hydrolysis rate constant at tropical temperature (30 °C) was 2.5 times higher than that at 20 °C, suggesting that sbCOD may be utilized for denitrification. During the SBR operation, high nitrification efficiency (93 ± 6%) was attained at low-DO condition (0.9 ± 0.1 mg O2/L). Utilizing sbCOD for post-anoxic denitrification in the SBR reduced the effluent nitrate concentration. Quantitative polymerase chain reaction, 16S rRNA amplicon sequencing and fluorescence in-situ hybridization revealed that the genus Nitrospira was a dominant nitrifier. 16S rRNA amplicon sequencing result suggested that 50% of the Nitrospira-related operational taxonomic units were affiliated with comammox, which may imply that the low-DO condition and the warm wastewater promoted their growth. The nitrogen removal in a tropical AO process was enhanced by incorporating low-DO nitrification and utilizing sbCOD for post-anoxic denitrification, which contributes to an improved energy sustainability of WWTPs.
Rivers as surface water in Malaysia are recipients of effluents and wastewater and yet it is important water source for daily uses of some villagers living along the river. Endocrine disruptors such as Bisphenol A (BPA) can be found in river due to continuous discharge into it. The objectives of this research is to find out the occurrence and concentration of BPA in Sungai Langat and also to see how water quality parameters such as temperature, pH, dissolved oxygen (DO), turbidity, Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and ammonia nitrogen (AN) affecting the concentration of BPA. 12 stations in total including upstream to downstream of Sungai Langat and also tributary of Sungai Langat. The instrument used to find out concentration of BPA is Triple Quadrupole LC/MS. The source of BPA are mainly industrial effluents and also direct domestic discharges. The water quality parameters that will affect concentration of BPA are Ammonia Nitrogen (AN), turbidity, Biochemical Oxygen Demand (BOD), Total Suspended Solid (TSS), and Chemical Oxygen Demand (COD), Dissolved Oxygen (DO). While pH and water temperature are also factors that will affect concentration of BPA but the significance is not shown in the analysis. It can be concluded that upstream of Sungai Langat has lower concentration of BPA than downstream.
A fed-batch strategy was established based on the maximum substrate uptake rate (MSUR) of Pseudomonas aeruginosa USM-AR2 grown in diesel to produce rhamnolipid. This strategy matches the substrate feed rates with the substrate demand based on the real-time measurements of dissolved oxygen (DO). The MSUR was estimated by determining the time required for consumption of a known amount of diesel. The MSUR trend paralleled the biomass profile of Ps. aeruginosa USM-AR2, where the MSUR increased throughout the exponential phase indicating active substrate utilization and then decreased when cells entered stationary phase. Rhamnolipid yield on diesel was enhanced from 0·047 (g/g) in batch to 0·110 (g/g) in pulse-pause fed-batch and 0·123 (g/g) in MSUR fed-batch. Rhamnolipid yield on biomass was also improved from 0·421 (g/g) in batch, 3·098 (g/g) in pulse-pause fed-batch to 3·471 (g/g) using MSUR-based strategy. Volumetric productivity increased from 0·029 g l(-1) h(-1) in batch, 0·054 g l(-1) h(-1) in pulse-pause fed-batch to 0·076 g l(-1) h(-1) in MSUR fed-batch.
Understanding the reaction mechanism that controls the one-electron electrochemical reduction of oxygen is essential for sustainable use of the superoxide ion (O2˙-) during CO2 conversion. Here, stable generation of O2˙- in butyltrimethylammonium bis(trifluoromethylsulfonyl)imide [BMAmm+][TFSI-] ionic liquid (IL) was first detected at -0.823 V vs. Ag/AgCl using cyclic voltammetry (CV). The charge transfer coefficient associated with the process was ∼0.503. It was determined that [BMAmm+][TFSI-] is a task-specific IL with a large negative isovalue surface density accrued from the [BMAmm+] cation with negatively charged C(sp2) and C(sp3). Consequently, [BMAmm+][TFSI-] is less susceptible to the nucleophilic effect of O2˙- because only 8.4% O2˙- decay was recorded from 3 h long-term stability analysis. The CV analysis also detected that O2˙- mediated CO2 conversion in [BMAmm+][TFSI-] at -0.806 V vs. Ag/AgCl as seen by the disappearance of the oxidative faradaic current of O2˙-. Electrochemical impedance spectroscopy (EIS) detected the mechanism of O2˙- generation and CO2 conversion in [BMAmm+][TFSI-] for the first time. The EIS parameters in O2 saturated [BMAmm+][TFSI-] were different from those detected in O2/CO2 saturated [BMAmm+][TFSI-] or CO2 saturated [BMAmm+][TFSI-]. This was rationalized to be due to the formation of a [BMAmm+][TFSI-] film on the GC electrode, creating a 2.031 × 10-9 μF cm-2 double-layer capacitance (CDL). Therefore, during the O2˙- generation and CO2 utilization in [BMAmm+][TFSI-], the CDL increased to 5.897 μF cm-2 and 7.763 μF cm-2, respectively. The CO2 in [BMAmm+][TFSI-] was found to be highly unlikely to be electrochemically converted due to the high charge transfer resistance of 6.86 × 1018 kΩ. Subsequently, O2˙- directly mediated the CO2 conversion through a nucleophilic addition reaction pathway. These results offer new and sustainable opportunities for utilizing CO2 by reactive oxygen species in ionic liquid media.
Matched MeSH terms: Oxygen; Reactive Oxygen Species
Climate change-induced abiotic stress results in crop yield and production losses. These stresses result in changes at the physiological and molecular level that affect the development and growth of the plant. Reactive oxygen species (ROS) is formed at high levels due to abiotic stress within different organelles, leading to cellular damage. Plants have evolved mechanisms to control the production and scavenging of ROS through enzymatic and non-enzymatic antioxidative processes. However, ROS has a dual function in abiotic stresses where, at high levels, they are toxic to cells while the same molecule can function as a signal transducer that activates a local and systemic plant defense response against stress. The effects, perception, signaling, and activation of ROS and their antioxidative responses are elaborated in this review. This review aims to provide a purview of processes involved in ROS homeostasis in plants and to identify genes that are triggered in response to abiotic-induced oxidative stress. This review articulates the importance of these genes and pathways in understanding the mechanism of resistance in plants and the importance of this information in breeding and genetically developing crops for resistance against abiotic stress in plants.
Vanadium-dependent haloperoxidases (V-HPO), able to catalyze the reaction of halide ions (Cl-, Br-, I-) with hydrogen peroxide, have a great influence on the production of halocarbons, which in turn are involved in atmospheric ozone destruction and global warming. The production of these haloperoxidases in macroalgae is influenced by changes in the surrounding environment. The first reported vanadium bromoperoxidase was discovered 40 years ago in the brown alga Ascophyllum nodosum. Since that discovery, more studies have been conducted on the structure and mechanism of the enzyme, mainly focused on three types of V-HPO, the chloro- and bromoperoxidases and, more recently, the iodoperoxidase. Since aspects of environmental regulation of haloperoxidases are less well known, the present paper will focus on reviewing the factors which influence the production of these enzymes in macroalgae, particularly their interactions with reactive oxygen species (ROS).
Training at high altitude for prolonged periods can cause low oxygen tension which can developed complication of hypoxia. Hypoxia is a cascade activity from a level of down regulation and function of cell’s nucleus. Early detection of biomarker and physiological changes are important in prevent the hypoxia at high altitude. Hyperbaric medicine is a new treatment that were used an oxygen therapy to treat hypoxic and inflammatory driven conditions which patients are treated with 100% oxygen at pressure greater than atmospheric pressure. The review discusses physiological changes associated with hypoxia, the response of biomarker hypoxia changes in high altitude and the role of hyperbaric oxygen therapy can play as part of the treatment for pilots and athletes training at high altitudes that suffering from disease with underlying hypoxia.
Throughout the cryopreservation process, plants were exposed to a series of
abiotic stresses such as desiccation and osmotic pressure due to highly concentrated
vitrification solution. Abiotic stress stimulates the production of reactive oxygen species
(ROS) which include hydrogen peroxide, superoxide radicals, and singlet oxygen. Higher
production of ROS may lead to oxidative stress which contributes to the major injuries in
cryopreserved explants. Antioxidant enzymes in plant such as ascorbate peroxidase
(APX) can protect plants from cell damage by scavenging the free radicals. This study was
determined based on APX enzyme activity of Aranda Broga Blue orchid’s protocorm-like
bodies (PLBs) in response to PVS2 (Plant Vitrification Solution 2) cryopreservation
treatments at different stages. PLBs that were precultured at 0.25 M sucrose for 3 days
were subjected to vitrification cryopreservation method. Results obtained showed that the
highest APX activity was achieved at PVS2 cryoprotectant treatment prior liquid nitrogen
(LN) storage. This phenomenon indicating that accumulation of osmotic and dehydrating
stress throughout the cryopreservation treatment resulted in oxidative burst which in turn
leads to higher APX activity in order to control the excess production of ROS. To
conclude, PVS2 treatment was revealed as the most detrimental step throughout
cryopreservation treatment. Thus, this research also suggested that exogenous
antioxidant such as ascorbic acid can be added throughout cryopreservation procedure
especially at PVS2 treatment in the future experiments to aid in regrowth of cryopreserved
explants by reducing oxidative stress.
Matched MeSH terms: Reactive Oxygen Species; Singlet Oxygen
Microbial fuel cell (MFC) is a promising technology that utilizes exoelectrogens cultivated in the form of biofilm to generate power from various types of sources supplied. A metal-reducing pathway is utilized by these organisms to transfer electrons obtained from the metabolism of substrate from anaerobic respiration extracellularly. A widely established model organism that is capable of extracellular electron transfer (EET) is Shewanella oneidensis. This review highlights the strategies used in the transformation of S. oneidensis and the recent development of MFC in terms of intervention through genetic modifications. S. oneidensis was genetically engineered for several aims including the study on the underlying mechanisms of EET, and the enhancement of power generation and wastewater treating potential when used in an MFC. Through engineering S. oneidensis, genes responsible for EET are identified and strategies on enhancing the EET efficiency are studied. Overexpressing genes related to EET to enhance biofilm formation, mediator biosynthesis, and respiration appears as one of the common approaches.
Radiation processing of food materials by gamma-radiation is a well-established method for
microbial decontamination and insect disinfestation. Irradiation of spices at doses ranging from
10 to 30 kGy has been reported to result in complete elimination of microorganisms with
negligible changes in the flavour quality. The effect of gamma-radiation on microflora and
vanillin content of cured vanilla beans in the dose range of 5 - 50 kGy has been investigated, but
its effect on other major aroma compounds and vanillin glucoside (vanillin aroma precursor)
remaining after curing have not been studied so far. Vanillin (4-hydroxy-3-methoxybenzaldehyde)
is one such compound used as a flavouring agent and as a dietary component. It is the major
component of natural vanilla, which is one of the most widely used and important flavouring
materials throughout the world. Vanillin is an antioxidant capable of protecting membrane
against lipid peroxidation and DNA against strand breaks induced by reactive oxygen species.
The present work was aimed to study the effect of gamma-radiation processing on the major
aroma compounds of cured vanilla beans and also to investigate possible enhancement in vanillin
content by the radiolytic breakdown of vanillin glucoside present already. Cured vanilla beans
were irradiated (5, 10, 15, 20 and 30 kGy) and the vanillin content of control and irradiated
samples were analysed, respectively for possible enhancement of vanillin content by radiolysis of
vanillin glucoside. Radiolytic breakdown of glycosidic precursors of aroma constituents and
consequent release of free aroma was shown to result in the enhancement of aroma quality of
these products. Since a considerable amount of vanillin exists as its glycosidic precursor in cured
vanilla pods, a possible enhancement in yield of vanillin by radiation processing is thus expected.
Hence the highly stable oxygen–carbon linkage between vanillin and glucose limits the possible
enhancement of aroma quality of irradiated beans.
Matched MeSH terms: Oxygen; Reactive Oxygen Species