Platinum is the most commonly used catalyst in fuel cell application. However, platinum is very expensive, thus limits the commercialisation of fuel cell system due to the cost factor. This study introduces a biosynthesis platinum from plant extracts that can reduce the cost of platinum production compared to the conventional method and the hazardous during the production of the catalyst. The biogenic platinum was tested on a Direct Methanol Fuel Cell. Advanced biogenic of Pt nano-cluster was synthesized through a novel and facile of one-pot synthesis bio-reduction derived from natural source in the form of plant extracts as reducing agent. Several selected plant extracts drawn from agricultural waste such as banana peel, pineapple peels and sugarcane bagasse extracts were comparatively evaluated on the ability of phytochemical sources of polyphenols rich for the development of single-step synthesis for Pt NPs. Notably, the biogenic Pt NPs from sugar cane bagasse has superior electro-catalytic activity, the enhanced utilization efficiency of Pt and appreciable stability towards methanol oxidation reaction, whose ECSA value approximates 94.58 m2g-1, mass activity/specific activity (398.20 mAmg-1/0.8471 mA/cm2Pt) which greater than commercial Pt black (158.12 mAmg-1/1.41 mA/cm2Pt).
3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) are processed-developed contaminants presence in vegetable oils after undergo refining process under excessive heat. Refined oils are extensively used in various frying applications, nevertheless, the reservation against their quality and safety aspects are of major concern to consumers and food industry. Realizing the importance to address these issues, this article deliberates an overview of published studies on the manifestation of 3-MCPDE and GE when vegetable oils undergo for frying process. With the modest number of published frying research associated to 3-MCPDE and GE, we confined our review from the perspectives of frying conditions, product properties, antioxidants and additives, pre-frying treatments and frying oil management. Simplicity of the frying process is often denied by the complexity of reactions occurred between oil and food which led to the development of unwanted contaminants. The behavior of 3-MCPDE and GE is closely related to physico-chemical characteristics of oils during frying. As such, relationships between 3-MCPDE and/or GE with frying quality indices - i.e. acidity in term of free fatty acid or acid value); secondary oxidation in term of p-anisidine value, total polar compounds and its fractions, and refractive index - were also discussed when oils were subjected under intermittent and continuous frying conditions.
The commercial application of liquid-state Pickering emulsions in food systems remains a major challenge. In this study, we developed a spray-dried Pickering emulsion powder using chitosan as a Pickering emulsifier and alginate as a coating material. The functionality of the powder was evaluated in terms of its oxidative stability, pH-responsiveness, mucoadhesivity, and lipid digestibility. The Pickering emulsion powder was oxidatively more stable than the conventional emulsion powder stabilized by gum Arabic. The powder exhibited pH-responsiveness, whereby it remained intact in acidic pH, but dissolved to release the emulsion in 'Pickering form' at near-neutral pH. The Pickering emulsion powder was also mucoadhesive and could be digested by lipase in a controlled manner. These findings suggested that the multi-functional Pickering emulsion powder could be a potential delivery system for applications in the food industry.
Methane-oxidizing bacteria (MOB) present in the water column mitigate methane (CH4) emissions from hydropower complexes to the atmosphere. By creating a discontinuity in rivers, dams cause large environmental variations, including in CH4 and oxygen concentrations, between upstream, reservoir, and downstream segments. Although highest freshwater methanotrophic activity is often detected at low oxygen concentrations, CH4 oxidation in well-oxygenated downstream rivers below dams has also been reported. Here we combined DNA and RNA high-throughput sequencing with microscopic enumeration (by CARD-FISH) and biogeochemical data to investigate the abundance, composition, and potential activity of MOB taxa from upstream to downstream waters in the tropical hydropower complex Batang Ai (Malaysia). High relative abundance of MOB (up to 61% in 16S rRNA sequences and 19% in cell counts) and enrichment of stable isotopic signatures of CH4 (up to 0‰) were detected in the hypoxic hypolimnion of the reservoir and in the outflowing downstream river. MOB community shifts along the river-reservoir system reflected environmental sorting of taxa and an interrupted hydrologic connectivity in which downstream MOB communities resembled reservoir's hypolimnetic communities but differed from upstream and surface reservoir communities. In downstream waters, CH4 oxidation was accompanied by fast cell growth of particular MOB taxa. Our results suggest that rapid shifts in active MOB communities allow the mitigation of CH4 emissions from different zones of hydropower complexes, including in quickly re-oxygenated rivers downstream of dams.
Transforming CO2 into fuels by utilizing sunlight is promising to synchronously overcome global warming and energy-supply issues. It is crucial to design efficient photocatalysts with intriguing features such as robust light-harvesting ability, strong redox potential, high charge-separation, and excellent durability. Hitherto, a single-component photocatalyst is incapable to simultaneously meet all these criteria. Inspired by natural photosynthesis, constructing artificial Z-scheme photocatalysts provides a facile way to conquer these bottlenecks. In this review, we firstly introduce the fundamentals of photocatalytic CO2 reduction and Z-scheme systems. Thereafter we discuss state-of-the-art Z-scheme photocatalytic CO2 reduction, whereby special attention is placed on the predominant factors that affect photoactivity. Additionally, further modifications that are important for efficient photocatalysis are reviewed.
The alginate lyase AlyQ from Persicobacter sp. CCB-QB2 is a three-domained enzyme with a carbohydrate-binding module (CBM) from family 32. The CBM32 domain, AlyQB, binds enzymatically cleaved but not intact alginate. Co-crystallisation of AlyQB with the cleaved alginate reveals that it binds to the 4,5-unsaturated mannuronic acid of the non-reducing end. The binding pocket contains a conserved R248 that interacts with the sugar's carboxyl group, as well as an invariant W303 that stacks against the unsaturated pyranose ring. Targeting specifically the non-reducing end is more efficient than the reducing end since the latter consists of a mixture of mannuronic acid and guluronic acid. AlyQB also seems unable to bind these two saturated sugars as they contain OH groups that will clash with the pocket. Docking analysis of YeCBM32, which binds oligogalacturonic acid, shows that the stacking of the pyranose ring is shifted in order to accommodate the sugar's axial C1-OH, and its R69 is accordingly elevated to bind the sugar's carboxyl group. Unlike AlyQB, YeCBM32's binding pocket is able to accommodate both saturated and unsaturated galacturonic acid.
Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, β-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E's biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[18F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([18F]F-γ-T-3) was prepared for this purpose. [18F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [18F]fluoride in DMF/K222. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [18F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [18F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [18F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues.
Surface functionalization and shape modifications are the key strategies being utilized to overcome the limitations of semiconductors in advanced oxidation processes (AOP). Herein, the uniform α-Fe2O3 nanocrystals (α-Fe2O3-NCs) were effectively synthesized via a simple solvothermal route. Meanwhile, the sulfonic acid functionalization (SAF) and the impregnation of α-Fe2O3-NCs on g-C3N4 (α-Fe2O3-NCs@CN-SAF) were achieved through complete solvent evaporation technique. The surface functionalization of the sulfonic acid group on g-C3N4 accelerates the faster migration of electrons to the surface owing to robust electronegativity. The incorporation of α-Fe2O3-NCs with CN-SAF significantly enhances the optoelectronic properties, ultrafast spatial charge separation, and rapid charge transportation. The α-Fe2O3-HPs@CN-SAF and α-Fe2O3-NPs@CN-SAF nanocomposites attained 97.41% and 93.64% of Cr (VI) photoreduction in 10 min, respectively. The photocatalytic efficiency of α-Fe2O3-NCs@CN-SAF nanocomposite is 2.4 and 2.1 times higher than that of pure g-C3N4 and α-Fe2O3, respectively. Besides, the XPS, PEC and recycling experiments confirm the excellent photo-induced charge separation via Z-scheme heterostructure and cyclic stability of α-Fe2O3-NCs@CN-SAF nanocomposites.
Activated carbons have been reported to be useful for adsorptive removal of the volatile anaesthetic sevoflurane from a vapour stream. The surface functionalities on activated carbons could be modified through aqueous oxidation using oxidising solutions to enhance the sevoflurane adsorption. In this study, an attempt to oxidise the surface of a commercial activated carbon to improve its adsorption capacity for sevoflurane was conducted using 6 mol/L nitric acid, 2 mol/L ammonium persulfate, and 30 wt per cent (wt%) of hydrogen peroxide (H2O2). The adsorption tests at fixed conditions (bed depth: 10 cm, inlet concentration: 528 mg/L, and flow rate: 3 L/min) revealed that H2O2 oxidation gave desirable sevoflurane adsorption (0.510 ± 0.005 mg/m2). A parametric study was conducted with H2O2 to investigate the effect of oxidation conditions to the changes in surface oxygen functionalities by varying the concentration, oxidation duration, and temperature, and the Conductor-like Screening Model for Real Solvents (COSMO-RS) was applied to predict the interactions between oxygen functionalities and sevoflurane. The H2O2 oxidation incorporated varying degrees of both surface oxygen functionalities with hydrogen bond (HB) acceptor and HB donor characters under the studied conditions. Oxidised samples with enriched oxygen functionalities with HB acceptor character and fewer HB donor character exhibited better adsorption capacity for sevoflurane. The presence of a high amount of oxygen functional groups with HB donor character adversely affected the sevoflurane adsorption despite the enrichment of oxygen functional groups with HB acceptor character that have a higher tendency to adsorb sevoflurane.
Fire is one of the major issues facing Southeast Asian peatlands causing socio-economic, human health and climate crises. Many of these fires in the region are associated with land clearing or management practices for oil palm plantations. Here we study the direct post-fire impacts of slash-and-burn oil palm agriculture on greenhouse gas emissions, peat physico-chemical properties and nutrient concentrations. Greenhouse gas (GHG) emissions were measured using Los Gatos ultraportable greenhouse gas analyser one month after a fire in dry season and five months after the fire event, in wet season. Surface soil samples were collected from each individual GHG measurement points, along with 50 cm cores from both burnt and non-burnt control areas for lab analyses. As an immediate post-fire impact, carbon dioxide (CO2) and methane (CH4) emissions, pH, electrical conductivity, and all macronutrient concentrations except nitrogen (N) were increased multi-fold, while the redox potential, carbon (C) and N content were greatly reduced in the burnt region. While some of the properties such as CO2 emissions, and electrical conductivity reverted to normal after five months, other properties such as CH4 emissions, pH and nutrient concentrations remained high in the burnt region. This study also found very high loss of surface peat C content in the burnt region post fire, which is irreversible. The results also show that surface peat layers up to 20 cm depth were affected the most by slash-and-burn activity in oil palm agriculture, however the intensity of fire can vary widely between different oil palm management and needs further research to fully understand the long term and regional impacts of such slash-and-burn activity in tropical peatlands.
This study demonstrates both the antioxidant and anticancer potential of the novel short molecule YT12 derived from peroxiredoxin (Prx) of spirulina, Arthrospira platensis (Ap). ApPrx showed significant reduction in reactive oxygen species (ROS) against hydrogen peroxide (H2 O2 ) stress. The complementary DNA sequence of ApPrx contained 706 nucleotides and its coding region possessed 546 nucleotides between position 115 and 660. Real-time quantitative reverse transcription polymerase chain reaction analysis confirmed the messenger RNA expression of ApPrx due to H2 O2 exposure in spirulina cells at regular intervals, in which the highest expression was noticed on Day 20. Cytotoxicity assay was performed using human peripheral blood mononuclear cells, and revealed that at 10 μM, the YT12 did not exhibit any notable toxicity. Furthermore, ROS scavenging activity of YT12 was performed using DCF-DA assay, in which YT12 scavenged a significant amount of ROS at 25 μM in H2 O2 -treated blood leukocytes. The intracellular ROS in human colon adenocarcinoma cells (HT-29) was regulated by oxidative stress, where the YT12 scavenges ROS in HT-29 cells at 12.5 μM. Findings show that YT12 peptide has anticancer activity, when treated against HT-29 cells. Through the MTT assay, YT12 showed vital cytotoxicity against HT-29 cells. These finding suggested that YT12 is a potent antioxidant molecule which defends ROS against oxidative stress and plays a role in redox balance.
Renewable solar energy is the key target to reduce fossil fuel consumption, minimize global warming issues, and indirectly minimizes erratic weather patterns. Herein, the authors synthesized an ultrathin reduced graphene oxide (rGO) nanosheet with ~47 nm via an improved Hummer's method. The TiO2 was deposited by RF sputtering onto an rGO nanosheet with a variation of temperature to enhance the photogenerated electron or charge carrier mobility transport for the photoanode component. The morphology, topologies, element composition, crystallinity as well as dye-sensitized solar cells' (DSSCs) performance were determined accordingly. Based on the results, FTIR spectra revealed presence of Ti-O-C bonds in every rGO-TiO2 nanocomposite samples at 800 cm-1. Besides, XRD revealed that a broad peak of anatase TiO2 was detected at ~25.4° after incorporation with the rGO. Furthermore, it was discovered that sputtering temperature of 120 °C created a desired power conversion energy (PCE) of 7.27% based on the J-V plot. Further increase of the sputtering temperature to 160 °C and 200 °C led to excessive TiO2 growth on the rGO nanosheet, thus resulting in undesirable charge recombination formed at the photoanode in the DSSC device.
The detection of phenolic compounds, i.e. resorcinol (RC) catechol (CC) and hydroquinone (HQ) are important due to their extremely hazardous impact and poor environmental degradation. In this work, a novel and sensitive composite of electrochemically reduced graphene oxide-poly(Procion Red MX-5B)/gold nanoparticles modified glassy carbon electrode (GCE/ERGO-poly(PR)/AuNPs) was assembled for voltammetric detection of benzenediol isomers (RC, CC, and HQ). The nanocomposite displayed high peak currents towards the oxidation of RC, HQ, and CC compared to non-modified GCE. The peak-to-peak separations were 0.44 and 0.10 V for RC-CC and CC-HQ, respectively. The limit of detections were 53, 53, and 79 nM for HQ, CC, and RC with sensitivities of 4.61, 4.38, and 0.56 μA/μM (S/N = 3), respectively. The nanocomposite displayed adequate reproducibility, besides good stability and acceptable recoveries for wastewater and cosmetic samples analyses.
Alzheimer's disease (AD) is a fatal neurodegenerative disease that requires immediate attention. Oxidative stress that leads to the generation of reactive oxygen species is a contributing factor to the disease progression by promoting synthesis and deposition of amyloid-β, the main hallmark protein in AD. It has been previously demonstrated that nanoyttria possesses antioxidant properties and can alleviate cellular oxidative injury in various toxicity and disease models. This review proposed that nanoyttria could be used for the treatment of AD. In this paper, the evidence on the antioxidant potential of nanoyttria is presented and its prospects on AD therapy are discussed.
Refined red palm olein (RPOo) is the first cooking oil that is a pro-Vitamin A source due to its high carotenoid concentration. The quality specifications from the manufacturers are usually applied to freshly produced oil. However, there is currently no information regarding the oxidative stability and phytonutrient content (Vitamin E and Carotene) for RPOo after prolonged storage time. The objective then is to study the effect of two local storage conditions and storage period(s) on the oxidative stability of RPOo. In this study, peroxide value (PV), p-anisidine value (AnV), induction period (IP), free fatty acid (FFA), and Vitamin E content were determined periodically for twelve months under local storage conditions (supermarket and kitchen). Carotene content, however, was determined only at initial and at the 12th month of storage time periods. It was found that there was an overall progressive but slow increase in PV and p-AnV. For PV, the storage effects were inconsistent. However, the effects were significant (p < 0.01) on the AnV throughout storage. At the end of the 12-months, for both storage conditions, the PV < 10 meq O2 g-1, the AnV < 10, the FFA < 0.2 % (palmitic acid), with a 30% drop in the total Vitamin E, and carotenoids content showed no significant drop (p < 0.01). The PV and AnV were also within Codex Alimentarius' recommended limits. Finally, the oxidative parameters showed that RPOo remains stable after year storage under the two simulated local storage conditions (the aforementioned supermarket and kitchen).
Sixty-four bottles of red palm olein and palm olein (constituted as control) samples were stored at permutations of common home setting variables which are: temperature (room temperature (24°C) or 8°C), light (kept in dark or exposure under light) and oxygen (opened or sealed caps). The effects of temperature, oxygen and light on the stability of red palm olein and palm olein were studied over 4 months of storage at simulated domestic conditions. The degree of auto- and photo-oxidations was evaluated by monitoring the following quality parameters: acidity, peroxide and p-anisidine values, fatty acids composition, carotenes and vitamin E. It is noted from the study that opened bottles of red palm olein was found to be stable for 4 months in comparison to its counterpart (palm olein) evidenced from their primary oxidative constituents (peroxides) and hydrolytic behavior (free fatty acids). Opened bottles are better off when stored at 8°C and protected from light for a longer shelf-life. Sealed bottles of palm olein showed better storage stability in the dark at 8°C; whereas sealed bottles of red palm olein was found to be stable at both temperatures studied without the influence of light. After 4 months of varying storage conditions, the fatty acid composition, vitamin E and carotenes of both oils remained unchanged. The phytonutrients in red palm olein rendered better storage stability when compared to palm olein.
Oleic acid is a mono-unsaturated fatty acid that can be found abundantly in various vegetable oils and potentially attractive to be used as raw material for epoxide chemical. In-situ epoxidation of oleic acid was conducted in batch reactor using peroxy-formic at 30-60°C. Pseudo-steady-state-hypothesis (PSSH) was applied to develop the kinetic model. Heterogeneous liquid-liquid system was chosen and four models which emphasized on the ring opening agent (ROA) and reversibility of the epoxidation reaction were proposed. It has been suggested that reversible model is well suited to represent the experimental data. Activation energy obtained from Arrhenius equation is in the range of 40-195 kJ/mol.
An investigation study was conducted in Bukit Merah Reservoir (BMR) for the assessment of arsenic concentration in the surface sediment in 23 sampling stations. The sediment samples were digested and analysed for arsenic using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Sediment parameters such as pH (4.42 ± 0.71), redox potential (121.77 ± 42.45 mV), conductivity (205.7 ± 64.07 μS cm-1) and organic matter (25.35 ± 9.34%) were also examined. The main objectives of this study are to determine the arsenic distribution and concentration and at the same time to assess the enrichment of arsenic using the geoaccumulation index (I geo ) and enrichment factor (EF). This study shows the total arsenic concentration in the surface sediment of BMR is 4.302 ± 2.43 mg kg-1 and found to be below the threshold value of Canadian Interim Sediment Quality Guidelines (ISQG). High arsenic concentration is recorded near the southern part of the lake where anthropogenic activities are prevalent. Based on I geo , 13% of sampling stations are categorised as moderately polluted, 52.2% as unpolluted to moderately polluted and the rest is categorised as unpolluted. EF shows 78.3% stations are classified as extremely high enrichment and the rest as very high enrichment. This finding provides important information on the status of arsenic contamination in BMR and creating awareness concerning the conservation and management of the reservoir in the future.
Among the various types of polyhydroxyalkanoate (PHA), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] has a high potential to serve as commercial bioplastic due to its striking resemblance to petroleum-based plastics. In this study, five different genotypes of Cupriavidusnecator transformants harbouring the phaCBP-M-CPF4 gene (including PHB¯4/pBBR1-CBP-M-CPF4) were developed to evaluate the efficiency of 3HHx monomer incorporation. The fraction of 3-hydroxyhexanoate (3HHx) monomer that was incorporated into the PHA synthesized by these C. necator transformants using palm oil as the sole carbon source, was examined. Overall, co-expression of enoyl-CoA hydratase gene (phaJ1) from Pseudomonas aeruginosa, along with PHA synthase (PhaC), increased the 3HHx composition in the PHA copolymer. The differences in the enzyme activities of β-ketothiolase (PhaACn) and NADPH-dependent acetoacetyl-CoA reductase (PhaBCn) of the C. necator mutant hosts used in this study, were observed to alter the 3HHx composition and molecular weight of the PHA copolymer produced. The 3HHx fractions in the P(3HB-co-3HHx) produced by these C. necator transformants ranged between 1 and 18 mol%, while the weight-average molecular weight ranged from 0.7 × 106 to 1.8 × 106 Da. PhaCBP-M-CPF4 displayed a typical initial lag-phase and a relatively low synthase activity in the in vitro enzyme assay, which is thought to be the reason for the higher molecular weights of PHA obtained in this study.
Glycerol electro-oxidation offers a green route to produce the high value added chemicals. Here in, we report the glycerol electro-oxidation over a series of multi walled carbon nano tubes supported monometallic (Pt/CNT and Pd/CNT) and bimetallic (Pt-Pd/CNT) catalysts in alkaline medium. The cyclic voltammetry, linear sweep voltammetry and chronoamperometry measurements were used to evaluate the activity and stability of the catalysts. The Pt-Pd/CNT electrocatalyst exhibited the highest activity in terms of higher current density (129.25 A/m²) and electrochemical surface area (382 m²/g). The glycerol electro-oxidation products formed at a potential of 0.013 V were analyzed systematically by high performance liquid chromatography. Overall, six compounds were found including mesoxalic acid, 1,3-dihydroxyacetone, glyceraldehyde, glyceric acid, tartronic acid and oxalic acid. A highest mesoxalic acid selectivity of 86.42% was obtained for Pt-Pd/CNT catalyst while a maximum tartronic acid selectivity of 50.17% and 46.02% was achieved for Pd/CNT and Pt/CNT respectively. It was found that the introduction of Pd into Pt/CNT lattice facilitated the formation of C3 products in terms of maximum selectivity achieved (86.42%) while the monometallic catalysts (Pd/CNT and Pt/CNT) showed a poor performance in comparison to their counterpart.