Lower Solution Research Articles

N-Type PVP/SWCNT Composite Films with Improved Stability for Thermoelectric Power Generation.

Single-walled carbon nanotubes (SWCNTs) are one of the promising thermoelectric materials in applications of powering wearable electronics. However, the electrical performance of n-type SWCNTs quickly decreases in air, showing a low stability, and low-cost and effective solutions to improving its stability are also lacking, all of which limit practical applications. In this study, we studied the stability of PVP/SWCNT composite films, where oxygen and moisture from air should be responsible for the decreased stability due to oxidation and hydration. In this case, we found that coating with a 0.20 g mL-1 PVP/0.002 g mL-1 PVDF layer on the surface of PVP/SWCNTs can prevent the penetration of oxygen and moisture from air, improving film stability, where there is almost no reduction in thermoelectric performance after they are exposed to air for 60 days. Based on the stable n-type PVP/SWCNT films, a thermoelectric generator was fabricated, where poly(dimethylsiloxane) (PDMS) was used to coat the surface of the thermoelectric leg to further improve its stability. This generator showed high output performance, which achieved an open-circuit voltage of 10.6 mV and a power density of 312.2 μW cm-2 at a temperature difference of 50 K. Particularly, it exhibited high stability, where the output performance kept almost unchanged after exposure to high-humidity air for 30 days. This coating technology is also applicable to other air-sensitive materials and promotes the development and application of thermoelectric materials and devices.

Toward Air Stability of Efficient Filter‐Free Band‐Selective Organic Photodetectors Based on Bulk Heterojunction: Avoiding Environmental Degradation with Atomic Layer Deposition Encapsulation

To detect the band‐specific optical signals used in many fields, it is necessary to develop spectrally selective photodetection. For such wavelength‐selective photodetection or color discrimination, organic photodetectors (OPDs) can offer significant benefits as low temperature and solution processability, chemical versatility, and specific spectral detection range. However, to avoid commonly used filters, the design of a narrowing approach that simultaneously achieves a selective detection range with a bandwidth of less than 50 nm and a spectral response of over 20% remains a challenge. OPDs based on charge‐collection‐narrowing principle can provide these features. In this approach, the detection window can be selected to match the absorption onset of the junction materials used in the bulk heterojunction layer. Herein, filter‐free band‐selective OPDs are realized based on PM6:PC70BM blends as state of the art. Fine adjustment over a bandwidth of 42 nm to be highly selective at 677 nm with a quantum efficiency of 48.4% under an inverse low bias of −2 V is reached. In addition, using a noninvasive and nondestructive encapsulation technique, it is demonstrated that these OPDs fully retain their high selective peak after 30 days storage in air.

Why should we use a low sodium dialysis solution for peritoneal dialysis?

Overhydration is highly prevalent in patients on peritoneal dialysis (PD), with inappropriately high sodium load supposedly playing a central role in the pathophysiology of the conditions. Recent studies have revealed the novel role of the interstitium as a buffer system for sodium ions, and it has been reported that patients on dialysis, including PD, present increased levels of sodium in the interstitium, such as in subcutaneous tissue and muscle. Hence, therapy for correction of overhydration should target the excess extracellular volume and the excess sodium storage in the interstitium. The ultrafiltrate obtained using the currently available PD solutions is hypo- to isonatric as compared to serum, which is disadvantageous for prompt and efficient sodium removal from the body in patients with overhydration. In contrast, use of low sodium PD solutions is characterised by iso- to hypernatric ultrafiltrate, which may beneficial for reducing sodium storage in the interstitium. Trials of low sodium PD solutions have reported possible clinical merits, for example, decreased blood pressure, reduced dryness of mouth and decreased body water content as assessed using bioimpedance methods. Given these observations and the high prevalence of overhydration in current PD populations, it makes medical sense that low sodium solutions be positioned as the new standard solution in the future. However, for medical safety, that is, to avoid hyponatremia and excessive decreases in blood pressure, further studies are needed to establish the appropriate compositions and applications of low sodium solutions.

Creating Healthy Environments for Schools: A Comprehensive Approach to Improving Nutrition in Arkansas Public Schools.

Nutrition plays a vital role in children's physical and emotional health. More than half of school age children's calories are provided in the school food environment, making school interventions an opportunity to address child nutrition. The Creating Health Environments for Schools (CHEFS) program is designed to leverage local resources to create customized solutions that improve the nutritional content of school food and encourage children to choose healthier food. There are 8 components: (1) customizing nutrition plans, (2) modifying/replacing menu items, (3) helping procure healthier food, (4) providing equipment grants, (5) training cafeteria staff, (6) implementing environmental changes and nudges, (7) engaging students and parents, and (8) supporting sustainability. Supporting child nutrition directors is key to facilitating cooperation with schools. Menu modifications and procurement are interrelated and depend on successfully collaborating with corporate, independent, and local food services organizations. Limited school budgets require low or no-cost solutions and staff training. Student and parent engagement are critical to facilitate culturally-appropriate solutions that increase awareness of healthy food. Every school district has particular resources and constraints. CHEFs engaged stakeholders to design customized solutions and encourage healthier nutrition for school children.

13 C NMR as an analytical tool for the detection of carbonic acid and pKa determination.

NMR spectroscopy has become a standard technique in studies both on carbon capture and storage. 13 C NMR allows the detection of two peaks for carbonated aqueous samples: one for CO2(aq) and another one for the species H2 CO3 , HCO3 - , and CO3 2- -herein collectively named Hx CO3 x-2 . The chemical shift of this second peak depends on the molar fraction of the three species in equilibrium and has been used to assess the equilibrium between HCO3 - and CO3 2- . The detection of H2 CO3 at low pH solutions is hindered, because of the concurrent liberation of CO2 when the medium is acidified. Herein, a valved NMR tube facilitates the detection of the Hx CO3 x-2 peak across a wide pH range, even at pH1.8 where the dominant species is H2 CO3 . The method employed the formation of frozen layers of NaH13 CO3 and acid solutions within the tube, which are mixed as the tube reaches room temperature. At this point, the tube is already securely sealed, preventing any loss of CO2 to the atmosphere. A spectrophotometry approach allowed the measurement of the actual pH inside the pressurized NMR tube. The chemical shift for H2 CO3 was determined as 160.33 ± 0.03 ppm, which is in good agreement with value obtained by DFT calculations combined with Car-Parrinello molecular dynamics. The H2 CO3 pKa value determined by the present method was 3.41 ± 0.03, for 15% D2 O aqueous medium and 0.8mol/L ionic strength. The proposed method can be extended to studies about analogs such as alkyl carbonic and carbamic acids.

Gastroenteritis Rehydration Of children with Severe Acute Malnutrition (GASTROSAM): A Phase II Randomised Controlled trial: Trial Protocol.

Children hospitalised with severe acute malnutrition (SAM) are frequently complicated (>50%) by diarrhoea ( ≥3 watery stools/day) which is accompanied by poor outcomes. Rehydration guidelines for SAM are exceptionally conservative and controversial, based upon expert opinion. The guidelines only permit use of intravenous fluids for cases with advanced shock and exclusive use of low sodium intravenous and oral rehydration solutions (ORS) for fear of fluid and/or sodium overload. Children managed in accordance to these guidelines have a very high mortality. The proposed GASTROSAM trial will reappraise current recommendations with mortality as the primary outcome. We hypothesize that liberal rehydration strategies for both intravenous and oral rehydration in SAM children with diarrhoea may reduce adverse outcomes. An open Phase II trial, with a partial factorial design, enrolling children in Uganda, Kenya, Nigeria and Niger aged 6 months to 12 years with SAM hospitalised with gastroenteritis (>3 loose stools/day) and signs of moderate and severe dehydration. In Stratum A (severe dehydration) children will be randomised (1:1:2) to WHO plan C (100mls/kg Ringers Lactate (RL) with intravenous rehydration (IV) given over 3-6 hours according to age including boluses for shock), slow rehydration (100 mls/kg RL over 8 hours (no boluses)) or WHO SAM rehydration regime (ORS only (boluses for shock (standard of care)). Stratum B incorporates all children with moderate dehydration and severe dehydration post-intravenous rehydration and compares (1:1 ratio) standard WHO ORS given for non-SAM (experimental) versus WHO SAM-recommended low-sodium ReSoMal. The primary outcome for intravenous rehydration is mortality to 96 hours and for oral rehydration a change in sodium levels at 24 hours post-randomisation. Secondary outcomes include measures assessing safety (evidence of pulmonary oedema or heart failure); change in sodium from post-iv levels for those in Stratum A; perturbations of electrolyte abnormalities (severe hyponatraemia <125 mmols/L or hypokalaemia. If the trial shows that rehydration strategies for non-malnourished children are safe and improve mortality in SAM this could prompt revisions to the current treatment recommendations or may prompt future Phase III trials.

Sodium functionalised carbon nanofibers draw solution for a solar-thermal forward osmosis water desalination system

Desalination offers the potential to bridge the demand-supply gap in the increasing global freshwater scarcity, with the forward osmosis (FO) technique appearing as an attractive solution amongst the various desalination technologies. However, the significant energy demand encountered during the draw-solute recovery process in FO desalination is considered the major anathema amongst other contending factors for which the allure of FO as a desalination technology becomes questioned. Consequently, a potentially innovative draw solution (DS) regeneration strategy, enabling the circumvention of the energy requirements associated with the recovery stage in FO desalination, is evaluated. The direct solar thermal FO (DSTFO) desalination concept is predicated on engineering and applying solar absorptive DS to directly leverage solar energy for solute recovery without recourse to electric power. In advancing the DSTFO concept, this study fabricated and evaluated a novel and highly osmotic sodium functionalised carbon nanofibres (Na/CNF) DS having a high osmotic pressure (93.9 bar), a low reverse solute flux (RSF) of 0.24 gMH, and a photothermal conversion efficiency of 63.49%, resulting in an evaporation rate of 1.85 kg/m2/hr under 2 suns of solar radiation. The DSTFO strategy offers a low-cost solution for enhancing water recovery and decreasing energy use in FO desalination systems.

Study of low manganese solution loss HAMO@ZrO2 via experimental and theory methodology

Lithium, being the lightest element in nature, has garnered attention for its potential to recover Li+ from brine. One of the promising materials in this context is spinel-structured lithium manganese oxide. Herein, a novel ZrO2 shell/Al3+ doped H1.6Mn1.6O4 core lithium ion sieve, namely, HAMO@ZrO2, was successfully prepared. XRD, SEM, HR-TEM, and XPS were used to characterize the morphological properties and crystal structure of HAMO@ZrO2. The equilibrium adsorption capacity (Qe) of HAMO@ZrO2 was found to be 36.89 mg·g−1. Furthermore, desorption equilibrium was achieved within 40 min when LAMO@ZrO2 was immersed in a 0.05 mol·L−1H+ solution, resulting in reduced manganese dissolution from 2.38 % to 1.4 %. The structural stability of HAMO@ZrO2 was explained using density functional theory (DFT), where the total structure energy was carefully estimated. Even after ten adsorption-desorption cycles, the Li+ adsorption capacity of HAMO@ZrO2 was sustained at 29.69 mg·g−1. The dissolution loss of Mn2+ (RMn2+) was less than 2 %, demonstrating the effective regeneration property of HAMO@ZrO2. In addition to its impressive properties, HAMO@ZrO2 exhibited high selectivity for Li+ over hetero-atoms in artificial brine. These findings make HAMO@ZrO2 a promising candidate for Li+ recovery applications.

Effects of Ca addition on microstructure, mechanical properties and corrosion behaviors of solution treated Mg-5Ga-xCa alloys

Effects of Ca addition on microstructure, mechanical properties and corrosion behaviors of solution treated Mg-5Ga-xCa (x = 0, 0.2, 0.5, 0.8 wt%) alloys are investigated. The Mg5Ga2 phase is almost dissolved into the matrix after solution treatment, while the residual phases mainly the Mg-Ga-Ca phase increases with the higher Ca content. The solution treated Mg-5Ga-0.2Ca alloy exhibits the highest corrosion resistance (with the average weight loss rate of 0.349 mg·cm−2·d−1 in Hank’s solution for 7 days) and the appropriate mechanical properties, with the ultimate tensile strength of 212 MPa and the elongation to rupture of 16.9%. Its high corrosion resistance can be mainly attributed to the protective effect of the Mg2Ca phase as a corrosion anode with low standard potential, the well-protected corrosion product film and the small grain size, while its good mechanical properties are due to the grain refinement and the solid solution strengthening of more Ga atoms. With a further increase in Ca content (≥0.5 wt%), although the grains are more refined, both the mechanical properties and corrosion resistance of the alloy decrease because of the residual phases in large quantities and low solution of Ga atoms.

Managing carbon waste in a decarbonized industry: Assessing the potential of concrete mixing storage

The effort towards a greener future will entail a shift to more environmentally friendly alternatives of many human activities. Within this context, the path towards a decarbonized society in general, and industrial decarbonization in particular, will require using low carbon solutions and/or capturing carbon emissions at the source. This flux of captured carbon will then require management and one option is to store it in concrete. The incorporation of the captured CO2 can be done during the mixing and/or curing. While the latter is more efficient and effective in terms of the amount of CO2 incorporated, it is limited to concrete in elements that are compatible with chamber curing. In practice, this would be restricted to the concrete pre-fabrication industry and, most probably, only to small size elements. Despite the lower performance, incorporation of CO2 into concrete during the mixing stage is a relatively universal alternative. The present research effort reveals that the latter solution is beneficial from an environmental point of view, with an estimated yearly carbon storage of 23 million tonnes worldwide against emissions of 2.5 million tonnes to do it.

Success Prediction of Crowdsourced Projects for Competitive Crowdsourced Software Development

Competitive Crowdsourcing Software Development (CCSD) is popular among academics and industries because of its cost-effectiveness, reliability, and quality. However, CCSD is in its early stages and does not resolve major issues, including having a low solution submission rate and high project failure risk. Software development wastes stakeholders’ time and effort as they cannot find a suitable solution in a highly dynamic and competitive marketplace. It is, therefore, crucial to automatically predict the success of an upcoming software project before crowdsourcing it. This will save stakeholders’ and co-pilots’ time and effort. To this end, this paper proposes a well-known deep learning model called Bidirectional Encoder Representations from Transformers (BERT) for the success prediction of Crowdsourced Software Projects (CSPs). The proposed model is trained and tested using the history data of CSPs collected from TopCoder using its REST API. The outcomes of hold-out validation indicate a notable enhancement in the proposed approach compared to existing methods, with increases of 13.46%, 8.83%, and 11.13% in precision, recall, and F1 score, respectively.

The impact of an ultrasonic standing wave on the sorption behavior of proteins: Investigation of the role of acoustically induced non-spherical bubble oscillations

HypothesisProtein molecules adsorb on the air/liquid interface due to possessing a hydrophobic side. A full surface coverage is important in many processes such as in protein harvesting by foam fractionation. The adsorption of proteins in low concentration solutions is preceded by a relatively long time lag known as the induction period. This has been attributed to the formation of an adsorbed monolayer, which relies on the reorientation of the protein molecules. The reduction of the induction period can significantly facilitate the sorption process to reach full protein coverage. For this purpose acoustically induced non-spherical bubble oscillations can aid in the formation of the monolayer and enhance the sorption process. ExperimentIn this study, low frequency ultrasound was used to induce non-spherical oscillations on an air bubble attached to a capillary. Profile analysis tensiometry was deployed to examine the effect of these non-spherical oscillations on the sorption dynamics of different proteins. FindingsWe observed that during the initial stages of adsorption, when the bubble surface is almost empty, non-spherical oscillations occur, which were found to significantly expedite the adsorption process. However, during later stages of the adsorption process, despite the continued presence of several sonication phenomena such as the primary radiation force and acoustic streaming, no change in adsorption behavior of the proteins could be noted. The occurrence, duration, and intensity of the non-spherical bubble oscillations appeared to be the sole contributing factors for the change of the sorption dynamics of proteins.

AviEar: An IoT-based Low Power Solution for Acoustic Monitoring of Avian Species

AviEar: An IoT-based Low Power Solution for Acoustic Monitoring of Avian Species

Embedded Low Power Blockchain Traceability Solution for University Classroom Attendance

The emergence of artificial intelligence and decentralized applications has made it possible to set up efficient systems in terms of traceability. The combined technologies are used in several fields such as fintech, industry 4.0, smart agriculture, etc. Their application can also impact educational and academic fields. There is growing interest in leveraging blockchain technology to securely store and retrieve student records. This paper proposes a new smart system that uses deep learning and blockchain technologies to store and manage student attendance. It relies on an embedded platform based on a camera and a Raspberry PI platform that uses artificial intelligence for face recognition and on the blockchain for secure data storage. Evaluating the resulting model on the Labeled Faces in the Wild (LFW) benchmark yields an impressive accuracy rate of 0.9938 with a standard deviation of 0.00272. Moreover, the proposed system provides a complete and accurate record of the entire student learning process, and, thus, reduces the risk of falsified educational records. It also provides potential benefits to future employers by giving them access to large amounts of verified and systematically accumulated data, allowing them to identify and hire qualified students.

Ti3C2Tx MXene reinforcement: a nickel-vanadium selenide/MXene based multi-component composite as a battery-type electrode for supercapacitor applications.

Designing innovative microstructures and implementing efficient multicomponent strategies are still challenging to achieve high-performance and chemo-mechanically stable electrode materials. Herein, a hierarchical three-dimensional (3D) graphene oxide (GO) assisted Ti3C2Tx MXene aerogel foam (MXene-GAF) impregnated with battery-type bimetallic nickel vanadium selenide (NiVSe) has been prepared through a hydrothermal method followed by freeze-drying (denoted as NiVSe-MXene-GAF). 3D-oriented cellular pore networks benefit the energy storage process through the effective lodging of NiVSe particles, improving the access of the electrolyte to the active sites, and alleviating volume changes during redox reactions. The 3D MXene-GAF conductive matrix and heterostructured interface of MXene-rGO and NiVSe facilitated the rapid transport of electrical charges and ions during the charge-discharge process. As a result of the synergism of these effects, NiVSe-MXene-GAF exhibited remarkable electrochemical performance with a specific capacity of 305.8 mA h g-1 at 1 A g-1 and 99.2% initial coulombic efficiency. The NiVSe-MXene-GAF electrode delivered a specific capacity of 235.1 mA h g-1 even at a high current density of 12 A g-1 with a 76.8% rate performance. The impedance measurements indicated a low bulk solution resistance (Rs = 0.71 Ω) for NiVSe-MXene-GAF. Furthermore, the structural robustness of NiVSe-MXene-GAF guaranteed long-term stability with a 91.7% capacity retention for successive 7000 cycles. Thus, developing NiVSe-MXene-GAF provides a progressive strategy for fabricating high-performance 3D heterostructured electrode materials for energy storage applications.

Perovskite solar cells prepared by processing CsPbBr&lt;sub&gt;3&lt;/sub&gt; nanocrystalline films in low temperature solution

&lt;sec&gt;In the process of preparing perovskite polycrystalline films by solution method, toxic solvents are used, and heat treatment is still the main way to induce perovskite grain growth, which not only increases energy consumption, but also hinders the development of flexible solar cells. In order to avoid the use of toxic solvents and high-temperature process, CsPbBr&lt;sub&gt;3&lt;/sub&gt; nanocrystal films are treated with low temperature solution to obtain corresponding polycrystalline thin films, which are applied to solar cells. Firstly, CsPbBr&lt;sub&gt;3&lt;/sub&gt; nanocrystalline (nanocrystalline NC) ink precursor is prepared by hot injection method, and nanocrystalline film is prepared by spinning coating method. In atmospheric environment, CsPbBr&lt;sub&gt;3&lt;/sub&gt; nanocrystalline films are prepared by saturated solution of Pb(SCN)&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;4&lt;/sub&gt;Br methyl acetate. Using the CsPbBr&lt;sub&gt;3&lt;/sub&gt; nanocrystalline film as an absorbing layer, the perovskite solar cell is prepared and the performance of the cell is effectively improved, and the efficiency of the cell reaches 8.43%. The results show that the saturated solution of Pb(SCN)&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;4&lt;/sub&gt;Br methyl acetate (MA) can not only continue the nanocrystalline crystallization, but also effectively passivate the defects in the perovskite films. In the process of preparing CsPbBr&lt;sub&gt;3&lt;/sub&gt; polycrystalline films, neither high temperature treatment nor the high boiling point toxic solvent is used, which is suitable for the preparation rigid and flexible solar cells.&lt;/sec&gt;&lt;sec&gt;The inorganic halide perovskite nanocrystals are developed and used as “ink” to fabricate fully air-processed, electrically stable solar cells. Although the prepared film is composed of mosaic nanocrystals capped with a large number of organic ligands and surface traps, this method provides a new approach for single-step, large-scale fabrication of inorganic perovskite devices. Moreover, the flexible control of the material composition provides a platform for uncovering the optimal conditions for optoelectronics and photonics.&lt;/sec&gt;

Reinforcement Learning-Based Nonautoregressive Solver for Traveling Salesman Problems.

The traveling salesman problem (TSP) is a well-known combinatorial optimization problem (COP) with broad real-world applications. Recently, neural networks (NNs) have gained popularity in this research area because as shown in the literature, they provide strong heuristic solutions to TSPs. Compared to autoregressive neural approaches, nonautoregressive (NAR) networks exploit the inference parallelism to elevate inference speed but suffer from comparatively low solution quality. In this article, we propose a novel NAR model named, which incorporates a specially designed architecture and an enhanced reinforcement learning (RL) strategy. To the best of our knowledge, is the first TSP solver that successfully combines RL and NAR networks. The key lies in the incorporation of NAR network output decoding into the training process. efficiently represents TSP-encoded information as rewards and seamlessly integrates it into RL strategies, while maintaining consistent TSP sequence constraints during both training and testing phases. Experimental results on both synthetic and real-world TSPs demonstrate that outperforms five state-of-the-art (SOTA) models in terms of solution quality, inference speed, and generalization to unseen scenarios.

Assessment of Biochar Adsorption Capacity for Ammonium and Nitrate and Implications on Soil Nitrogen Management

Biochar has the potential to retain soil nitrogen (N), but inconclusive results are reported. This study aimed to examine the adsorption behavior of ammonium (NH4+) and nitrate (NO3−) onto biochar and the pH effects to assess retention capability and elucidate the impact on N management. Laboratory experiments were conducted to determine adsorption capacity of NH4+ and NO3− onto seven biochar products from different feedstocks and Pyrolysis Temperature (PT). All products exhibited adsorption capacity for NH4+ with most isotherms fit well by Langmuir and/or Freundlich equations except one by linear equation. Almond shell biochar from 550 °C PT showed the highest adsorption for NH4+ in the solution concentration range of 1–200 N mg L−1. Almond shell biochar from 900 °C PT had the lowest adsorption capacity at low solution concentration, but adsorption increased linearly and surpassed all other products as concentration increased. Two softwood biochar products (500 and 540 °C PT) showed a similar trend. Further, NH4+ adsorption was highly pH dependent (peaked around pH 9 for all products but reduced by more than half at neutral pH). Except for the almond char at 900 °C PT, no adsorption of NO3− was observed for other products at 5 or 50 mg N L−1 initial solution concentration. The results concluded that the ability to retain N retention by biochar without modification is limited and varied among feedstocks and pH. The role of biochar to improve N availability or use efficiency should not be overstated to avoid mismanagement decision making.

High-Resolution Sensor System to Investigate Solute Transport in Saturated Sediments

Highlights Innovative sensor system was developed to detect solute transport at very high time resolutions. The sensors measure electrical conductivity as voltage drops at a frequency of up to 10 Hz, allowing for detailed solute breakthrough curves (BTCs). One-dimensional solute transport equations were modeled numerically using the finite differences technique, and the results show good agreement between the modeled BTCs and those obtained in the laboratory for all materials. Abstract. Hyporheic exchange flow, the movement of river water into streambed sediments and its subsequent return to the surface water after suffering biogeochemical transformations, impacts a stream’s water quality and ecology. These processes, which are the basis for the self-purification capacity of river systems, depend on the quantity and travel time of the flow within the sediments. Different tracer-based approaches have been deployed for studying flow in saturated sediments, but few of these experimental methodologies are able to attain the high temporal resolutions that are needed to adequately capture the passage of a solute plume in a porous medium. To allow for a better description of such flows, we designed and fabricated an innovative, low-cost sensor system able to detect solute transport at multiple locations simultaneously at very high time resolutions. The sensors measure electrical conductivity as voltage drops at a frequency of up to 10 Hz, allowing for detailed solute breakthrough curves (BTCs). The fabricated sensors were tested in a laboratory experimental setup designed to examine solute transport under conditions that reproduce 1D flow in saturated sediments. The sensor system was able to successfully detect electrical conductivity (expressed as voltage drop) in real-time, at high temporal resolution, and at multiple locations. Solute BTCs collected with the system were consistent and highly repeatable under the same conditions. One-dimensional solute transport equations were modeled numerically using the finite differences technique, and the results showed good agreement between the measured and modeled BTCs for all materials. The proposed system is inexpensive compared to conventional EC probes, easy to operate, and sensitive to low solute concentrations. Keywords: Hyporheic exchange flow, Saturated sediments, Sensor, Solute transport.

Iron oxide fluxing and precipitation in sulphate deposits during heat-resistant alloy corrosion in simulated combustion gas

Two ferritic alloys, Fe-25Cr and Fe-25Cr-2Mn-1Si, and two austenitic alloys, Fe-25Cr-20Ni and 310SS, coated with a thin film of Na2SO4-K2SO4 mixture were exposed to a flowing wet CO2 gas at 650 and 750 °C for up to 300 h. In addition to oxide scaling, a new manifestation of Fe oxide fluxing into the salt layer was observed. The effects of alloy composition and reaction temperature on this phenomenon were determined. The process is attributed to formation of a low melting Na2O-Na2SO4 solution in the early stages of reaction, followed by basic fluxing of FeO and/or Fe3O4.