Areas Of Low Activity Research Articles

Passively Sampled Ambient Hydrocarbon Abundances in a Texas Oil Patch

The United States has experienced exceptional growth in oil production via unconventional extraction for over a decade. This boom has led to an increase in hydrocarbon emissions to the atmosphere. With Texas as the leading contributor to growing oil production, it is important to assess the effects the boom has had on the environment and communities at local and regional levels. We conducted a pilot study to investigate the use of passive samplers for evaluating potential off-site risk from hydrocarbon emissions in a relatively low production activity area of the Texas Eagle Ford shale. Emissions from production sites include benzene, a hazardous air pollutant and known carcinogen. Passive hydrocarbon sampling devices (Radiello samplers) were used to monitor hydrocarbon levels on a rural property near a production site with an occasional flare for one year. Selected hydrocarbons were analyzed using thermal desorption and gas chromatography with flame ionization detection. Benzene concentrations were found to be correlated with changes in season, with higher abundance in the winter months. Benzene levels at this site were similar or higher than those observed in urban areas, away from shale oil and gas production. Increased benzene concentrations were distinguished when winds advected hydrocarbons from the production site, suggesting that oil and gas site emissions have a greater impact on the local community when winds advect them towards those living downwind; however, hydrocarbon levels in this low production area never exceeded state air monitoring comparison standards.

Assessment of Acoustical Level in Healthcare Design: In Comparison with the Standards of World Health Organization


 
 This research was undertaken to assess acoustical conditions in the hospital environment, researcher aimed at investigating sound levels of local hospitals and to evaluate how much their current status complied with recommendations levels given by World Health Organization. To assess the actual noise impact, sound levels of six local hospitals were measured using non – probability sampling technique at five different locations of every hospital i.e. Waiting Area, Emergency Department, Corridor, Intensive Care Unit and General Ward. All readings obtained during morning, afternoon and night intervals were then compared with World Health Organization acoustic guidelines for hospitals (30-40dB) Findings revealed that sound levels of all hospitals studied were significantly high as compared to standards given by WHO, the hypothesis was significant with p<.005, twice as high sound levels were observed in comparison to the recommended limits. Equivalent continuous sound levels (Leq) in most hospitals of Lahore ranged between (70-80dB), irrespective of time of the day, indicating a serious issue of noise pollution. Results also indicated that the highest sound levels were observed in waiting area at Hameed Latif hospital (110dBA). While the lowest sound levels were observed in Intensive Care Unit of Sheikh Zayed hospital (59dBA), which despite being the lowest were high in comparison to standards given by World Health Organization. Furnishings and interiors of a hospital usually have easy-to-clean surfaces that are hard and reflective in order to prevent infections, but such surfaces tend to propagate noise into the patient rooms and down the corridors causing sound to reverberate. Optimal sound levels in hospitals can only be achieved through regular sound assessment, proper zoning of high and low activity areas and use of sound absorbing materials in building design that do not compromise hygiene requirements of the place. Only then patients can truly receive the quality of care they deserve.
 

Background DNA on flooring: The effect of cleaning

The collection and detection of ‘background’ DNA (bDNA) from items submitted for forensic DNA sampling is a common occurrence when sampling surfaces for DNA left behind following an activity of interest. There are a number of factors that might affect the presence of bDNA on a surface, one of which is cleaning of the surface. Here, we investigate the impact of household cleaning methods on the presence of bDNA on flooring in five homes occupied by known and unrelated individuals. Two adjacent samples were collected pre- and post-cleaning from areas of high and low activity on floors within the kitchen, living room, bedroom and bathroom (i.e. four samples per room). Floors were cleaned by the participant according to their normal routine, with methods and products varying between rooms and homes. Overall, slightly greater quantities of DNA were obtained from samples taken prior to cleaning compared to post-cleaning. Further, major contributors were more frequently assigned in profiles from samples obtained pre-cleaning, although the number of contributors was generally greater in these profiles. This study highlights the need to consider domestic cleaning histories of a surface from which a sample is collected.

Synthesis of PANi nanoarrays anchored on 2D BiOCl nanoplates for photodegradation of Congo Red in visible light region

Photocatalytic processes have attained considerable attention of late years, especially for environmental remediation. Despite extensive research in this area, the need for safer, more efficient, and cost-effective processes has encouraged researchers to develop novel photocatalysis. However, the low active surface area and narrow bandgap limit their photocatalytic performances. In the present research, the 2D BiOCl sheets were successfully synthesized by a new hydrothermal method and decorated by PANi nanoarrays through in-situ oxidative polymerization of aniline. The UV–vis diffuse-reflectance and photoluminescence spectroscopy revealed the synergistic effects between PANi nanoarrays and 2D BiOCl by enhancing the absorption in the visible light region and reduction of bandgap down to 2.9 eV. Furthermore, the morphology analysis showed the proper decoration of PANi nanoarrays on 2D BiOCl nanoplates. The synthesized nanocomposite with different weight loadings of PANi was taken to evaluate the decolorization efficiency of it. The result exhibited an optimum value of 88.35% at 60 min irradiation under visible light in the photodegradation of Congo Red (CR). Moreover, the probable photocatalytic mechanism for degradation of CR by PANi/BiCOl photocatalyst was proposed based on the scavenger experiments. The outcomes indicated that the PANi promoted the absorption intensity of the pure BiOCl in the visible region. To that, the well-arranged array and considerably high specific surface area of PANi could encourage the transfer of electrons witch generated by the photo to 2D BiOCl substrate and repel the recombination of electron-hole pairs.

Effective enhancement of electrochemical energy storage of cobalt-based nanocrystals by hybridization with nitrogen-doped carbon nanocages

Cobalt-based oxygenic compounds Co(OH)2, CoO and Co3O4 are attractive for electrochemical energy storage owing to their high theoretical capacities and pseudocapacitive properties. Despite the great efforts to their compositional and morphological regulations, the performances to date are still quite limited owing to the low active surface area and sluggish charge transfer kinetics. Herein, different Co-based nanocrystals (Co-NCs) were conveniently anchored on the hierarchical nitrogen-doped carbon nanocages (hNCNCs) with high specific surface area and coexisting micro-meso-macropores to decrease the size and facilitate the charge transfer. Accordingly, a high specific capacity of 1170 F g−1 is achieved at 2 A g−1 for the Co(OH)2/hNCNCs hybrid, in which the capacitance of Co(OH)2 (2214 $${\rm{F\;g}}_{\rm{Co({OH})_2}}^{ - 1}$$ ) is approaching to its theoretical maximum (2595 F g−1), demonstrating the high utilization of active materials by the hybridization with N-doped nanocarbons. This study also reveals that these Co-NCs store/release electrical energy via the same reversible redox reaction despite their different pristine compositions. This insight on the energy storage of Co-based nanomaterials suggests that the commonly-employed transformation of the Co-NCs from Co(OH)2 to CoO and Co3O4 on carbon supports is unnecessary and even could be harmful to the energy storage performance. The result is instructive to develop high-energy-density electrodes from transition metal compounds.

Constructing efficient quasi-solid-state alkaline Ni–Fe battery based on Ni–Mn hydroxides/Ni3S2 and FeOOH@RGO electrodes

Alkaline Ni–Fe battery has attracted extensive attentions due to low cost, fast preparation and easy portability. However, the energy-storage capacity of Ni–Fe battery is greatly restricted by low active area and poor electronic conductivity, so it is highly desirable to design suitable electrode materials. In our work, Ni–Mn hydroxides/Ni3S2 (Ni2Mn1-S) nanohybrid with nanosheet structure was successfully fabricated via tuning the Mn content and reaction conditions. The orderly open structure, heterogeneous Mn atoms and even-distributed Ni3S2 phase not only generate more electrochemical active sites, but also significantly promote electronic conductivity, thus enhancing electrochemical performance of hybrid structure. Servered as supercapacitive electrode, the Ni2Mn1-S presents high capacitance (1386.8 C g−1 at 1 A g−1), excellent rate performance (71% retention at 30 A g−1) and suitable cycling stability (79% retention after 5000 cycles). After the coating of RGO nanosheet, the FeOOH@RGO electrode achieves high capacity performance (180 C g−1 at 1 A g−1) and rate performance (66% retention even at 10 A g−1). Furthermore, quasi-solid-state Ni–Fe battery was developed, utilizing a positive Ni2Mn1-S electrode and a negative FeOOH@RGO electrode. The hybrid device could achieve high energy densities (53.8 Wh kg−1 at 820 W kg−1 and 26.2 Wh kg−1 at 8200 W kg−1) and still maintain 75% capacitance after enduring 5000 cycles, which attributes to fast diffusion dynamics of Ni2Mn1-S and FeOOH@RGO electrodes.

Characteristics and underlying physics of ionic wind in dc corona discharge under different polarities**Project supported by China Postdoctoral Science Foundation (Grant No. 3020036721801) and Electrostatic Research Foundation of Liu Shanghe Academicians Experts Workstation, Beijing Orient Institute of Measurement and Test, China (Grant No. BOIMTLSHJD20181005).

During a dc corona discharge, the ions’ momentum will be transferred to the surrounding neutral molecules, inducing an ionic wind. The characteristics of corona discharge and the induced ionic wind are investigated experimentally and numerically under different polarities using a needle-to-ring electrode configuration. The morphology and mechanism of corona discharge, as well as the characteristics and mechanism of the ionic wind, are different when the needle serves as cathode or anode. Under the different polarities of the applied voltage, the ionic wind velocity has a linear relation with the overvoltage. The ionic wind is stronger but has a smaller active region for positive corona compared to that for negative corona under a similar condition. The involved physics are analyzed by theoretical deduction as well as simulation using a fluid model. The ionic wind of negative corona is mainly affected by negative ions. The discharge channel has a dispersed feature due to the dispersed field, and therefore the ionic wind has a larger active area. The ionic wind of positive corona is mainly affected by positive ions. The discharge develops in streamer mode, leading to a stronger ionic wind but a lower active area.

Spatial differences in genetic diversity and northward migration suggest genetic erosion along the boreal caribou southern range limit and continued range retraction.

With increasing human activities and associated landscape changes, distributions of terrestrial mammals become fragmented. These changes in distribution are often associated with reduced population sizes and loss of genetic connectivity and diversity (i.e., genetic erosion) which may further diminish a species' ability to respond to changing environmental conditions and lead to local population extinctions. We studied threatened boreal caribou (Rangifer tarandus caribou) populations across their distribution in Ontario/Manitoba (Canada) to assess changes in genetic diversity and connectivity in areas of high and low anthropogenic activity. Using data from >1,000 caribou and nine microsatellite loci, we assessed population genetic structure, genetic diversity, and recent migration rates using a combination of network and population genetic analyses. We used Bayesian clustering analyses to identify population genetic structure and explored spatial and temporal variation in those patterns by assembling networks based on R ST and F ST as historical and contemporary genetic edge distances, respectively. The Bayesian clustering analyses identified broad‐scale patterns of genetic structure and closely aligned with the R ST network. The F ST network revealed substantial contemporary genetic differentiation, particularly in areas presenting contemporary anthropogenic disturbances and habitat fragmentation. In general, relatively lower genetic diversity and greater genetic differentiation were detected along the southern range limit, differing from areas in the northern parts of the distribution. Moreover, estimation of migration rates suggested a northward movement of animals away from the southern range limit. The patterns of genetic erosion revealed in our study suggest ongoing range retraction of boreal caribou in central Canada.

Investigating the Effect of Lewis Acid Base Interaction in Non-Stoichiometric Vanadium Oxide Based CNFs in Lithium – Sulfur Battery

Despite the potential of lithium-sulfur batteries to reach practical energy densities of 500–600 Wh/kg, there are still many problems plaguing their development. The sulfur cathode suffers from low electrochemical utilization and poor cycle life owing to the insulating nature of S and the Li2S discharge product, and the shuttling of lithium polysulfide species especially at high areal mass loadings. Enormous progress has been achieved in terms of capacity and static life during the past few years to overcome these issues, by employing various carbon and inorganic materials (metal oxides, metal-organic frameworks). Recently, non-stoichiometric metal oxides have been employed as sulfur host materials due to their high conductivity and ability to bind polysulfides chemically through unsaturated metal ion sites. However, the formation of metal-suboxides involves a high-temperature calcination process, which usually results in dense host materials with lower accessible surface area, and a reduced host/polysulfide interaction. Moreover, these studies are often reported with low sulfur loadings (1–2 mg/cm2) resulting in lower areal capacity. Herein, we report the use of electrospun vanadium monoxide/carbon nanofibers (VCNFs) as cathode host in Li-S batteries, which provide high electrical conductivity for better sulfur utilization and strong Lewis acid-base interaction with polysulfides to suppress shuttle. The developed cathode possesses hierarchical micro-mesoporous architecture with inter-fiber spacing and a high surface area of 181 m2/g. The unique architecture overcomes the challenges associated with dense, low active surface area based powered oxide materials. The developed VCNFs-S cathodes with a high sulfur loading of 3 mg/cm2 exhibit initial discharge capacities of ∼1350, ∼1247, and ∼1113 mAh g–1 at 0.1, 0.2, and 0.5 C rates, respectively, with long-term cycling (Fig 1a) over 200 cycles at 0.5 C rate. Moreover, at ~7mg/cm2, Li-S cells exhibit high areal capacity of 8 mAh/cm2 at a current density of C/10 up to 50 cycles (Fig 1b). The high surface area results in active reaction sites spread throughout the VCNFs, improving the accessible reaction area for better binding of polysulfides, enabling the smooth operation at high-loading in Li-S system. Using postmortem X-ray photoelectron spectroscopy analysis, this study reveals the presence of strong Lewis acid–base interaction between VO (3d3) and Sx 2– through the coordinate covalent V–S bond formation. Additionally, freestanding nature of the cathodes eradicate the need of additional inactive elements, viz., binders, additional current collectors (Al-foil), and additives. Our results highlight the importance of developing high surface area metal-suboxides/monoxide-based conducting polar host materials for next-generation Li–S batteries. Figure 1

Electrochemical promotion of methane oxidation over nanodispersed Pd/Co3O4 catalysts

Abstract During the last two decades the Electrochemical Promotion of Catalysis (EPOC) phenomenon has been studied extensively for many catalytic reactions including hydrocarbon oxidation reactions and hydrogenations. In the majority of the studies, the catalysts/electrodes consisted of porous noble metal films (Pt, Pd, Rh) prepared, for instance, by calcination of organometallic pastes. This results in low metal dispersion and low active surface area, limiting therefore the overall catalytic activity. In view of further practical application of the EPOC phenomenon to industrial catalysts, we should be able to enhance the activity of nanodispersed materials. In this study, for the very first time, we observed an enhanced catalytic activity of a Pd nanodispersed catalyst supported on a porous Co3O4 semiconductor film. The Pd/Co3O4 composite powder was deposited on an yttria-stabilized zirconia (YSZ) solid electrolyte without the presence of an interlayer film. The observed enhancement was non-Faradaic, with Faradaic efficiency values as high as 80. The Pd/Co3O4 catalyst was characterized thoroughly by means of a wide variety of physicochemical techniques, such as TEM, SEM, TGA, ICP and BET. In addition, this material was further compared with a classical Pd/YSZ metallic film, prepared by calcination of an organometallic paste. This allows for a comparison of metal-support interactions (MSI) and the EPOC effect. Using supported catalysts as catalytic films for electrochemical promotion studies may lead to the practical utilization of EPOC in the chemical industry or in gas exhaust treatment.

Landscaping of Residential Estates as a Mitigation Measure to Reduce Carbon Dioxide and Temperature Levels in Inner Ibadan City, Nigeria

This study assessed the spatial distribution of carbon dioxide emanation in selected residential estates and the impact of landscaping in reducing their levels in Ibadan metropolis. The study was carried out in high, medium and low commercial activity areas characterized by population density and traffic congestion within Ibadan city. CO<SUB>2</SUB> concentrations and temperature were measured at 4 hourly interval from 9am to 5pm for a period of seven consecutive days while numbers of trees/plants (biomass density) were counted, at 21 different points from seven areas each with high, medium and low commercial activities. Measurements were carried out with the aid of calibrated portable gas meters. The means CO<SUB>2</SUB> (ppm) were 542±95, 415±11 and 376±14 at 1.00 pm in the high, medium and low commercial activity areas respectively. CO<SUB>2</SUB> concentrations were generally higher than IPCC value, but highest in the afternoon. Temperature values were generally higher in the afternoon in high and medium commercial activity areas, but lower in the low commercial activity zones. Significantly, density of trees in low commercial activity areas (234.3±6.7) was higher compared to those in medium (22.8±0.5) and high (24.2±0.7) activity areas respectively. An inverse correlation was observed between CO<SUB>2</SUB> concentration and the density of trees (r=-0.456; p=0.038). The spatial distribution of CO<SUB>2</SUB> concentration in relation to landscaping revealed that CO<SUB>2</SUB> concentration reduces northward away from the urban core areas where there were fewer trees. The areas with low commercial activities had large numbers of trees while temperature and CO<SUB>2</SUB> flux were lower in these areas. Temperature and density of trees contribute significantly in explaining the CO<SUB>2</SUB> concentration (p=0.015). CO<SUB>2</SUB> concentrations and temperature were high in high commercial activities areas in Ibadan metropolis, few or no trees were observed in those areas. Increase in density of trees could be attributed to decrease in the CO<SUB>2</SUB> concentration. Hence, tree planting needs to be encouraged in the urban core of Ibadan metropolis to reduce air pollution.

Пространственное-временное сопоставление сейсмичности и изостатических аномалий вдоль Срединно-Атлантического хребта

The structure of a spatial-temporal distribution of seismic activity along the Mid-Atlantic Ridge (MAR) according to teleseismic data is characterized by areas of increased activity that are marked on spatial-temporal cross-sections with stripes of event concentration, divided by inactive areas of low seismic activity that are marked on cross-sections with gaps. The areas with increased seismic activity matching minimums of isostasy can be interpreted as local areas of hot mantel injection reflected in gravity anomalies and seismic activity stable both over time and in position. These areas exist in the MAR segments that are characterized by a low-temperature and low-depth magmatic activity of “spreading” type. The gaps in seismic activity were observed in the areas of highly productive magmatic activity of “plume” type, where the mantle with lower viscosity and low tectonic stress is distributed. Wide stripes of high seismic activity coincide with shear fracture zones with high amplitude lateral discontinuity of MAR axis. The stripes of seismic activity matching the local maximums of isostasy can either mark transform faults, where shear type seismic events are registered, or highly productive “plume” magmatism with increased seismic activity, where the magmatic activity leads to a volcanic activity that forms sea floor peculiarities observed in gravity anomalies.

Alpha particle autoradiography for high spatial resolution mapping of radionuclides

An autoradiographic technique capable of determining the spatial location of radioactive isotopes within materials on the scale of micrometers is demonstrated in low-activity mineral samples, where the concentrations of radionuclides with short half lives is small and below the detection limits of current measurement techniques. The location of certain radionuclide species within samples with complex structures on the micron scale can yield valuable information, however current methods do not have the spatial resolution required for this purpose.We demonstrate the use of an autoradiographic emulsion to directly image alpha particle events in samples with low radionuclide concentrations, allowing spatial resolution of radionuclide locations on the order of several microns. Exposure over a long time period allows sufficient integration of decay events enabling analysis of samples with low activity but large area, (less than 1×10−4 Bq/mm2). The use of polarising filters to increase contrast between the alpha particle tracks and the substrate during imaging demonstrates the viability of the technique on samples with a complex structure.

Heterogeneous public and local knowledge provides a qualitative indicator of coastal use by marine recreational fishers

Marine recreational fishing (MRF) benefits individuals and economies, but can also impact fish stocks and associated ecosystems. Fish are an important resource providing direct economic benefit through commercial and recreational exploitation, and more esoteric ecosystem services. It is important to consider recreational fishing in marine spatial planning, but spatial information on coastal utilisation for MRF is frequently lacking. Public sources of local knowledge were reviewed and the frequency of unique references to sites extracted. Sites were georeferenced using a gazetteer compiled from the Ordnance Survey and United Kingdom Hydrographic Office named sea features gazetteer and local knowledge sources. Recreational fishing site densities were calculated across 2700 km of coastline and this proxy indicator of coastal utilisation validated against two independent surveys using permutative Monte Carlo sampling to control for sparse and non-independent data. Site density had fair agreement with independent surveys, but standardization by shore length reduced this agreement. Applying a 3 by 3 box filter convolution to the spatial layers improved the agreement between local knowledge derived predictions of activity and those of directed surveys, and permutation testing showed that agreement did not arise as a result of the convolution itself. High and low activity areas were more accurately predicted than areas of intermediate activity. Site density derived from heterogeneous participant and local knowledge can produce qualitative predictions of where recreational fishers fish, and applying a convolution can improve the predictive power of data so derived. However, this approach will be subject to unquantifiable bias and may fail to identify areas highly valued by marine recreational fishers. Thus it should be used in conjunction with other information in decision making and may be best suited to inform the early stage sampling design of on-site surveys or to complement other data sets in mapping areas of importance to recreational fishers.

Neural Network Inspired Design of Highly Active and Durable N-Doped Carbon Interconnected Molybdenum Phosphide for Hydrogen Evolution Reaction

Molybdenum phosphide, as a promising electrocatalyst for the hydrogen evolution reaction (HER), its activity suffers from two main limitations: low active surface area and unsatisfactory electrical conductivity. Herein, inspired by the neural network, we construct a novel artificial neural network-like molybdenum phosphide composite (denoted as MoP@NC-MF), using three-dimensional (3D) melamine resin foams as the scaffold. The neural network-like MoP@NC-MF composite consists of carbon-wrapped MoP nanoparticles of abundant active sites as the “neurons” and N-doped carbon as the “axons”. The MoP@NC-MF composite exhibits high electrocatalytic activity and stability for HER with a low overpotential of 125 mV required to achieve a current density of 10 mA cm–2 and a small Tafel slope of 53.0 mV dec–1 under acidic conditions, which is one of the best HER electrocatalysts among the reported single molybdenum phosphide materials. Such a superior performance of the MoP@NC-MF composite is attributed to the unique neural network structure with both abundant MoP active sites to speed the surface reactions and the interconnected carbon “axons” to promptly transfer electrons. Additionally, the 3D network structure facilitates the liquid reactants/gaseous products transporting to/escaping from the reaction centers. Our findings demonstrate that elaborated design of the morphology and the structure can achieve highly efficient electrocatalysts.

Development and Evaluation of Ir Based Anode Electrocatalysts for Water Electrolysis

Introduction Hydrogen production through PEM type water electrolysis followed by hydrogen storage and use has been focused on as one of the efficient uses of renewable energy. Although PEM type water electrolyzer has an advantage on reduced ohmic resistance between two electrodes, it has also a disadvantage that common carbon supports cannot be used in order to disperse small catalyst particles under the high potential condition over 1.5 V at the anode. That leads to low active surface area of anode electrocatalysts, resulting in high cost. Therefore, the purpose of this study is to develop carbon-free porous anode electrocatalysts with high active surface area. So far, our group has been working on mesoporous carbon materials for PEFC studies1, and we have found that such a porous structure is kept even after being built into the device and can improve the mass transfer within catalyst layers. Then, basic concepts of mesoporous carbon are applied to this study. We propose development of carbon-free porous metal catalysts to enhance the performance of water electrolyzer. Experimental method Ir(acac)3 and Pluronic F127 were used as a metal precursor and a template to form a porous structure, respectively. A mixture of the metal precursor, solvent, and surfactant was heated up by step-by-step treatments in N2 or Air atmosphere to make the porous structure. After the fundamental material characterizations of the resulting Ir material, electrochemical measurements were performed using a common half-cell setup in the acidic solution. Oxygen evolution reaction (OER) activity was evaluated as anode electrocatalysts. Also, membrane electrode assembles (MEAs) were developed, and then a single cell performance was evaluated. Results and discussion Based on nitrogen sorption measurements and a SEM image as shown in Figure 1, the porous structure consisted by aggregation of particles was confirmed for the obtained Ir material. The resulting pore diameter was mostly smaller than 70 nm. When OER activity of porous Ir material was measured and compared with commercial IrO2 electrocatalyst (Figure 2), initial OER activity was lower than IrO2. This was due to fact that porous Ir material is mainly composed by Ir metal, which was confirmed by XRD. Then, the surface of porous Ir was activated via electrochemical oxidation. As a result, activated porous Ir/IrOx showed equivalent OER activity to commercial IrO2 as seen in Figure 2. Even though OER activity was just equivalent to commercial IrO2 as powder, the difference was seen when electrocatalysts were built into MEAs. The details of IV characteristics will be discussed. Furthermore, we have also worked on durability analyses against potential fluctuation derived by renewal energy, which will be also discussed. Reference (1) Hayashi, et al., Electrochim. Acta, 53, 6117-6125 (2008). Figure 1

A new type of terbium diselenide nano octagon integrated oxidized carbon nanofiber: An efficient electrode material for electrochemical detection of morin in the food sample

A new type of terbium diselenide (Tb2Se2) was prepared in the structure of nano octagon and integrated with oxidized carbon nanofiber (f-CNF) by using a simple hydrothermal technique. The oxidation of CNF and the formation of f-CNF/Tb2Se2 nanocomposite were studied by using various analytical techniques such as TEM, FT-IR, Raman, XRD and XPS analysis. In addition, the electrochemical properties of f-CNF/Tb2Se2 nanocomposite modified glassy carbon electrode (GCE) were studied by using the electrochemical techniques such as CV and DPV techniques, which showed low charge transfer resistance (Rct = 7.26 Ω) and high active surface area (A = 0.113 cm2). Meanwhile, the CV of ferricyanide at this electrode showed a low peak potential separation (ΔEp = 0.060 V). Furthermore, the reported f-CNF/Tb2Se2/GCE exhibited an excellent electrochemical activity towards the detection of morin. As expected, f-CNF/Tb2Se2/GCE exhibited high sensitivity (1.07 μA μM−1 cm−2) and acceptable detection limit (0.6 μM) of morin. In addition, f-CNF/Tb2Se2/GCE was found with feasible selectivity, stability, and reproducibility. Finally, the real sample analysis also stated the exclusive performance of f-CNF/Tb2Se2/GCE electrode towards the detection of morin in guava leaves extract.

Noble Design for Highly Active and Stable PEM Electrocatalyst Using Synergistic Interaction between Pt, TiO2 and Carbons

As interest in climate change has increased in recent years, research on alternative energy sources is becoming more active. Fuel cells are one of the most promising electrochemical energy conversion devices that hold many advantages. In particular, polymer electrolyte fuel cells (PEMFCs) are attracting much attention due to their high power density and relatively good portability. In PEMFC systems, the main cost is due to the catalyst in terms of high cost of platinum group metals. This derives the need to understand the way how to get a highly active and stable electrocatalysts. In general, Pt/C is most widely used catalyst because it has a large surface area for platinum anchoring, high electrical conductivity, and suitable pore structure for transferring reactant and product. However, carbon support undergoes carbon corrosion which is happened thermodynamically favored in fuel cell operation conditions. This phenomenon occurs at the surface of the carbon and it makes void places under the Pt nanoparticles. This mechanism causes losing electrochemical active sites. And there are also agglomeration and sintering of Pt particles on the carbon surface. Consequentially, carbon corrosion and platinum dissolution result in reduced electrochemical surface area (ECSA) and interferes long-term operations. Thus, electrochemically stable support materials need to be developed. In various alternative material candidates, our group selected the TiO2 based support because it exhibits excellent chemical stability under severe acidic condition and offers the opportunity to modifying electronic structure of platinum particles. However, hindrances such as low electrical conductivity, catalytic activity, and surface area limit the direct use of TiO2 as a catalyst support. To remedy these drawbacks, we have designed carbon-titania composite support based electrocatalysts. These noble TiO2 – carbon hybrid support was synthesized from electrospun nanofibers and platinum nanoparticles are deposited on a support by microwave-assisted polyol process. Through our new approaches, we can obtain the electrocatalysts which have a unique 3D pore structure with higher surface area, modified electronic structure with increased intrinsic activity and extended cyclic durability.

Mesoporous Metal Electrocatalysts for the Oxygen Evolution Reaction

Introduction Development of anode electrocatalys for the PEM type water electrolyzer is challenging since carbon supports cannot be used in order to disperse small catalyst particles under the high potential condition over 1.5 V. Without carbon supports, electrocatalysts result in relatively low active surface area and low activity. Our group has been working on mesoporous materials for PEFC and has found that mesoporous materials can keep their porous structure even after being built into the device. Based on the similar idea used in our PEFC studies, we propose development of carbon-free mesoporous metal electrocatalysts with high active surface area to increase the efficiency of water electrolyzer cells. In this study, mesoporous platinum and iridium materials were particularly developed, and their oxygen evolution reaction (OER) activity was evaluated. Experimental method Mesoporous platinum and mesoporous iridium materials were synthesized using Pt(acac)2 or Ir(acac)3 as a metal precursor and Pluronic F127 as a surfactant. After mixing the surfactant and metal precursor, the resulting mixture was heated up under N2 or Air atmosphere to decompose Pluronic F127 and make the mesoporous structure. Their electrochemical measurements were performed using a common half-cell setup in the solution, in order to evaluate OER activity. The durability against high potential like 1.8 V was also analyzed. Results and discussion The resulting platinum and iridium materials were confirmed to have the randomly oriented porous structure constructed by aggregation of Pt and Ir/IrOx nanoparticles, respectively. The pore diameter was found mostly smaller than 100 nm. With these porous metal materials, OER activity was evaluated. Regarding platinum based materials, the initial activity resulted in the same as a standard Pt/KB electrocatalyst, TEC10E50E, even though ECSA was six times higher for Pt/KB. However, for their durability, as expected, Pt/KB lost most of OER activity owing to carbon corrosion. Consequently, carbon-free porous Pt electrocatalyst with high activity and durability was successfully prepared. Similarly, a porous iridium electrocatalyst has been prepared, and its OER activity will be discussed.

Impacts of anthropogenic pressures on the contemporary biogeography of threatened crocodilians in Indonesia

AbstractThe Greater Sunda region of South-east Asia supports a rich diversity of economically and ecologically important species. However, human pressures are reshaping contemporary biogeography across the region. Megafaunal distributional patterns have been particularly affected because of deforestation, poaching and human–wildlife conflict. Crocodilians are at the centre of these conflicts in Indonesia and yet remain poorly studied across much of the archipelago. We conducted population surveys of salt-water crocodiles Crocodylus porosus and false gharials Tomistoma schlegelii in Sumatra, and examined whether crocodile abundance and distribution are correlated with variations in human disturbance, fishing pressure, and habitat type. We then used these data to model remaining suitable habitat for T. schlegelii across South-east Asia. We found that abundance of T. schlegelii and C. porosus was correlated with distance from human settlements, and fish-trapping pressure. We recorded the presence of T. schlegelii in a river system in which it was previously unknown, thus expanding the known range of the species. We also found that the predicted remaining suitable habitat for T. schlegelii in Indonesia is largely limited to areas of low human activity. From these empirical and modelling approaches we propose several key conservation priorities: (1) eliminate the use of fish traps in remaining patches of T. schlegelii habitat, (2) prioritize crocodile population surveys in remaining suitable habitat, particularly in remote areas, (3) consider T. schlegelii to be potentially Endangered locally in Sumatra, and (4) expand existing reserves around the Lower Kampar River and Berbak National Park/Sembilang National Park areas of Sumatra.