Gravimetric Monitoring Research Articles

Smart Refractory Sensors Development for Corrosion and Erosion Monitoring in High Temperature Systems

To optimize the operation and functioning of high temperature systems such as slagging gasifiers, coal boilers and glass/steel melters, it is important to monitor corrosion and erosion of refractory used in such systems. Corrosion test strategies are generally based on continuous gravimetric and chemical reactivity monitoring at operational temperatures (750°-1500°C). Both thermocouples and failure sensors and arrays would be useful to monitor the health of any refractory or coatings in these systems. Many of such type of sensors are installed into the systems through open access ports within the refractory; however, there are some disadvantages of this approach where corrosive/erosive gas and molten materials can penetrate and compromise the system. The current work presents the development and performance demonstration of smart refractory with embedded high temperature sensors such as thermocouples, thermistors, and various spallation/crack monitoring sensors, which may be used within a variety of refractory brick in different high temperature processes and applications.The main feature of this technology is that electroceramic based sensors are embedded into smart refractory without significantly impact to the intrinsic properties of the refractory. This technology circumvents the need to insert an isolated monolithic, stand-alone sensor into the refractory via an access port. This technological approach guarantees the integrity and the chemical stability of the materials used in the sensor fabrication within the harsh environment and does not introduce molten material (such as slag) penetration pathways within the refractory. One interesting and important aspect of this innovation is that these embedded sensors can be used to in situ monitoring processes such as chemical reactions and at the same time give information and a deeper understanding of the corrosion and erosion process of the refractory within the system.As stated above, the objective of our work is to develop high-temperature sensors composed of electroceramic materials that are chemically stable at high temperatures (750°-1500°C) and high pressures (up to 1000 psi) that can be used in monitoring corrosion and erosion process in refractory used in high energy systems. The high-temperature sensors investigated in this work were composed of various oxide composites directly embedded into the refractory oxides. The composites used for this work were synthesized by a mixed-oxide route. Metal oxides were inserted within a matrix material composed of refractory oxides (Al2O3, ZrO2, etc.). The physical and electrical properties were specifically manipulated by altering the level of percolation of the conductive species (metal oxides) within the refractory constituent (refractory oxide).Prior to the development of the high-temperature sensors, the oxides composites developed in this study were sintered up to 1600°C under oxidizing atmosphere in order to investigate densification, microstructural evolution, phase development, and their thermoelectrical performance as a function of the composition. The 4-point DC conductivity measurements were performed between 100°-1500°C. The sensors were fabricated from the composite materials by 3D-printing or screen-printing methods into the refractory brick during the consolidation process.An example of one of these embedded sensors consisted of an electroceramic-based thermocouple fabricated with two separate oxide composite compositions which were patterned to produce a couple within the interior of a refractory matrix. The thermocouple successfully displayed thermoelectric voltage trend (as a function of temperature), and the voltage was 220.0 mV around 1400 °C.Corrosion tests on the refractory embedded sensors were performed. To evaluate corrosion in the refractory brick an in-house glass composition was prepared and pressed into pellets and delivered into a pre-cut cavity in the brick. Corrosion experiments results showed the glass penetrated the brick over a 90 h period, and the penetration of the glass through the brick could be monitored by both a amperometric and voltametric based sensor. With this experiment, it was demonstrated that the embedded sensor could dynamically monitor the corrosion process. Acknowledgements: This work was supported by the United States Department of Energy (DOE) through the research project grant (DE-FE0031825). The authors would also like to acknowledge the technical support of Dr. Qiang Wang, Dr. Marcela Redigolo and Mr. Harley Hart of WVU Shared Research Facilities (SRF) for assistance in characterization and technical input.

Corrosion inhibition behaviour of synthetic 2-(phenylsulphonamido)-3-methylbutanoic acid on mild steel in alkaline solution

The corrosion inhibiting behaviour of synthetic 2-(phenylsulphonamido)-3-methylbutanoic acid (PSMBA) on mild steel in the presence of 0.1 M KOH was investigated using combined gravimetric, electrochemical and theoretical simulation corrosion monitoring methods. The gravimetric data showed that the inhibitor effectively protected the metal from alkaline corrosion and that the inhibition ability depended on concentration increase and reduced gradually with prolonged immersion time. The electrochemical impedance spectroscopy results show that the charge transfer resistance increased with the addition of the inhibitor while potentiodynamic polarization results showed that the corrosion current density decreased upon the addition of the inhibitor, theoretical simulation results revealed a low and comparable energy gap between the LUMO and HOMO energies. All these showed that 2-(phenylsulphonamido)-3-methylbutanoic acid functioned as a good corrosion inhibitor for mild steel in alkaline medium.

PLGA implants for controlled dexamethasone delivery: Impact of the polymer chemistry

The aim of this study was to better understand the impact of the chemistry of poly(lactic-co-glycolic acid) (PLGA) polymers on the resulting drug release kinetics from implants prepared by melting and molding. Dexamethasone was incorporated as the drug. The polymer molecular weight of the PLGA, lactic acid:glycolic acid ratio and type of end groups (ester versus free acid) were varied. The implants were characterized using optical macroscopy, SEM, X-ray powder diffraction, DSC, gravimetric monitoring of dynamic changes in the systems’ dry and wet mass upon exposure to the release medium as well as drug release and pH measurements. Interestingly, the shape of the drug release profiles was similar in all cases: No noteworthy burst effect was observed. Dexamethasone release set on after a lag time, the length of which strongly depended on the PLGA chemistry: The lag time decreased with decreasing polymer molecular weight, increasing glycolic acid content and was shorter for –COOH end groups compared to ester end groups. In all cases, drug release set on as soon as a critical hydrophilicity and polymer molecular weight were reached and substantial system swelling started: The penetration of large amounts of water into the implants allowed for complete dexamethasone dissolution and relatively rapid diffusion of the dissolved drug molecules through a highly swollen PLGA gel up to 100% drug release.

Dodecylamine encapsulation in layered smectite clay mineral: Release and application for copper corrosion inhibition in 0.1 M nitric acid solution

The economic and environmental impact associated to the use of corrosion inhibitors for metal protection directs research works towards systems based on the encapsulation of these active principles for a more sustainable approach. Here, dodecylamine (DA) was intercalated in the interlayer space of a smectite and the intercalated amine once released, was used as copper corrosion inhibitor in 0.1 M nitric acid solution. The effective synthesis of the organoclay was confirmed by X-ray diffraction, infrared spectroscopy and thermogravimetric analysis. The inhibition percentages obtained by electrochemical methods increased with the release time (from 55% after 0.5 h to 90% after 24 h). This result indicates a slow release of intercalated amine present in the organoclay. Gravimetric monitoring of corrosion experiments performed continuously for 28 days confirm the decrease of copper corrosion rate with release time. Based on thermodynamic studies and surface analysis by scanning electron microscopy, the released amine was physiosorbed on copper surface, leading to the formation of a film that protect the metal against nitrates and dissolved oxygen, responsible of the cathodic reactions that initiates copper corrosion.

High-Precision Gravimetric Monitoring Provides Insights into Subsurface Processes

Summary Monitoring of time-lapse changes in gravity has been carried out for decades, and measurement repeatability with relative spring gravimeters has in recent years improved to 0.6–2 µGal (standard deviation) for area surveys. This is better than often cited vendor specification. Gravimeters based on other physical principles offer high absolute accuracy or improved time-lapse sensitivity. All these may open possibilities for monitoring smaller and deeper subsurface changes and over shorter time intervals, with applications in hydrocarbon and geothermal production, gas and CO2 storage, hydrology, volcanology and more. Survey design and data processing are integral parts of a program. Sensor redundancy and repeat measurements provide opportunities for in-situ calibrations. An example from a gas accumulation shows a reduction in gravity of about 3 µGal and subsidence of 5–6 mm over 8 years. Both signals are clearly above the noise level and are likely to have been caused by production from a neighbouring structure. The information can quantify the amount of reservoir pore pressure drop, size of gas cap expansion and vertical movements of the gas-liquid contact to a precision well below 1 m.

Выявление природных и техногенных разуплотненных зон в подработанном массиве по данным высокоточных гравиметрических наблюдений

The paper presents the results of gravimetric studies at the potassium salt deposit in order to obtain information on the development of negative engineering-geological processes in the rock mass caused by subsoil development. A methodology was developed for high-precision monitoring gravimetric observations, which makes it possible to determine the change in the field over time. A physico-geological model of gravimetric monitoring, representing a homogeneous geological medium with an isolated area in which rock density changes have occurred, has been created. For the purposes of gravimetric monitoring, a method for processing and interpreting dynamic gravity anomalies based on the synthesis of qualitative and quantitative methods for extracting geological information from gravimetric data has been adapted. The result of the interpretation is the area of distribution, the probable interval of depths of rock decompaction, as well as the magnitude of the change in rock density, which characterizes the intensity of the process of decompaction. Examples are given of testing the developed technology for dividing decompressed zones into natural and man-made zones at the Verkhnekamskoye potash deposit in order to improve the safety of its operation. It is shown that the results of monitoring gravimetric observations can predict areas of dangerous geological processes and control subsidence of the earth's surface.

Geodynamic hazards and risk assessment at the Karachaganak oil, gas, and condensate field

The geodynamic hazards and risk assessment at the Karachaganak oil, gas, and condensate field (KOGCF) were explored on the northern board of the Pre-Caspian Basin to predict the consequences of the long-term exploitation of this field. We integrate multiple measurements, including repeated accurate leveling, Global Positioning System (GPS) measurements, and high precision gravimetric and seismological monitoring at the KOGCF. The results of geodynamic monitoring at the KOGCF for the first time made it possible to prove noticeable seismic deformation processes in the sedimentary cover under the influence of hydrocarbon production. The vertical displacements and horizontal movement along faults, changes in local gravity anomalies, and earthquake sources at depths comparable to hydrocarbon production intervals at the KOGCF have been identified. The maximum amplitudes of modern vertical movement of the earth's surface and the minimum values of the differently oriented horizontal movement were revealed within the projection on the ground surface of the crest of the carbonate massif (Upper Devonian-Lower Permian age). The results suggest the expansion of uneven compression in the crest of the KOGCF while tension processes occur on its periphery. There is a decrease in gravity variations in relation to the slopes of this massif in areas with active hydrocarbon production. An extended zone of high-gradient steps of ΔGa anomalies, spatially coinciding with the position of fault zones, is mapped along the periphery of the contour of production wells. In the northeastern part of the KOGCF, seismic events were registered practically in the depth intervals of the productive horizons from which hydrocarbons are produced. A spatial relationship between the seismic events and the anomalous deformation activity in the northeast KOGCF has been revealed. Consequently, the field development has provoked both intense deformation of the earth's surface and weak local seismicity.

Optimization of an information system module for solving a direct gravimetry problem using a genetic algorithm

Optimal approaches to solving many problems are required in many areas. One of these areas is the determination of the occurrence of gravity anomalies in oil and gas fields. In this paper is proposed a new approach for determining the source of gravity anomalies in an oil and gas fields by estimating the gravity parameters associated with simple-shaped bodies such as a homogeneous sphere, a horizontal prism, and a vertical step. The approach was implemented in the computational module of the GeoM information system for optimizing the solution of a series of direct gravimetry problems using a genetic algorithm (GA). Approach is based on solving the direct gravimetry problem to minimize the discrepancy of gravity variations by the genetic algorithm. The method allows to select values simultaneously for several parameters of the studied environment. The task is realized through successive approximations based on a given initial approximation of the medium. The paper indicates the initial calculation parameters and criteria for finding optimal solutions for models of the geological environment. The calculations were carried out for such models of the environment as a homogeneous sphere, a horizontal prism and a vertical ledge. For calculations, the results of gravimetric monitoring at one of the Kazakh oil and gas fields were used. The paper demonstrates the operation of the algorithm and presents the results of modeling for three available field profiles. The obtained results of the system showed an acceptable accuracy of the algorithm up to 10-11. The genetic algorithm made it possible to significantly increase the reliability of the model and reduce the working time for analyzing the measured gravitational field

Measurement and Monitoring of Particulate Matter in Construction Sites: Guidelines for Gravimetric Approach

Studies on particulate matter (PM) from construction activities are still at an early stage. Thus, there is still no consensus on standardized experimental methods for monitoring PM in construction sites, which impedes the advancement of knowledge on this subject. This work proposes guidelines for measuring and monitoring the concentration of suspended PM and the annoyance generated by sedimented particles on construction sites in urban areas. These guidelines aim to reduce the variability and uncertainties that exist during the PM sampling processes at construction sites. This study adopts a literature review strategy in order to update the available scientific literature based on empirical evidence obtained in experimental PM studies and relevant documents from government agencies. The proposed guidelines were applied in a study protocol for gravimetric monitoring PM and annoyance tracking generated by sedimented particles using sticky pads. As a result, this article details sampling techniques, procedures, and instruments, focusing on gravimetric sampling, highlighting their characteristics compared to other monitoring approaches. Additionally, it points out a series of parameters for the measurement and monitoring of PM. This paper seeks to support future researchers in this area, inform decision making for experimental sampling, and provide a benchmark for measuring and monitoring PM at construction sites.

Minimum Detectable Mass and Volume Fluxes During Magmatic Recharge at High Prominence Volcanoes: An Application to Erciyes Dağ Volcano (Turkey)

Magma reservoir recharge is widely recognised as a precursor of eruptive activity. However, the causative relationships between reservoir rejuvenation and surface observables such as gravitational potential field changes and ground deformation are still poorly understood. At intermediate and silicic intra-plate volcanoes where crustal mechanical heterogeneity combined with high-prominence are expected to fundamentally affect the crustal stress and strain relationship, protracted period of repose and absence of monitoring data raise questions about the detectability of magma recharge. Here we report results from integrated geodetic forward modelling of ground displacements and gravity changes from reservoir recharge at Erciyes Dağ, a large prominence (∼2,800 m), yet poorly studied, stratovolcano of the Central Anatolian Volcanic Province in Turkey. The most recent eruption at ∼7000 BC, close proximity to the Kayseri Metropolitan Area and absence of dedicated volcano monitoring set a precedent to explore stealth magmatic processes at the volcano. Using finite element analysis we systematically explore the influence of subsurface mechanical heterogeneities and topography on surface deformation and gravity changes from magmatic recharge of Erciyes Dağ’s reservoir. We show that whilst crustal heterogeneity amplifies ground displacements and gravity variations, the volcano’s substantial prominence has the opposite effect. For generic reservoir pressure and density changes of 10 MPa and 10 kg m−3 predicted vertical displacements vary by a factor of 5 while residual gravity changes vary by a factor of 12 between models ignoring topography or mechanical heterogeneity and those that do not. We deduce reservoir volume and mass changes of order 10–3 km3 and 1010 kg, respectively, at the detectability limit of conventional surveying techniques at the volcano. Though dependent on model assumptions, all results indicate that magma recharge at Erciyes Dağ may go undetected at fluxes 1) sufficient to maintain an active reservoir containing eruptable magma and 2) similar to those reported for intermediate/silicic volcanoes with repose times of 100–1,000s of years (e.g., Parinacota) and persistently active mafic volcanoes such as Mt. Etna and Stromboli. Our findings may be utilised to inform integrated geodetic and gravimetric monitoring at Erciyes Dağ and other large prominence silicic volcanoes and could provide early insights into reservoir rejuvenation with implications for the development of disaster risk reduction initiatives.

A Mechanistic Understanding of Electrochemical Bistability Induced By the Presence of 1,10-Phenanthroline in the Cathodic Deposition of Copper

We report herein a precise control of the electrochemical bistability induced by surface area changes during the cathodic deposition of copper. Small additions of 1,10-phenanthroline (Phen) in the reaction media present an inhibiting effect on the global rate mainly due to the adsorption of protonated Phen. The increase of its concentration favors a shrinkage of the bifurcation diagram and shifts it to less negative potentials. The dynamic instability is verified by impedance measurements, and a negative impedance is clearly found. We calculated the apparent molar mass of the adsorbents using in situ gravimetric monitoring in the electrochemical experiments, and the results indicate that mass changes occur mainly due to the reduction of copper from bivalent ions dissolved in the reaction media. Importantly, the adsorption of protonated Phen molecules does not show a considerable contribution in mass variations but prevents the formation of a copper course grained morphology over the surface. Imaging analysis indicates finer nodulations at the lower branch compared to the upper branch in the bistability domain. On the basis of these observations, a kinetic mechanism is proposed and a good agreement is obtained between the apparent molar mass extracted from experiments and the theoretical values. Altogether, our results contribute to a detailed physicochemical description of the nonlinear behavior, bringing new insights about this reaction and pointing out the possibility to design switchable surface electrodes by taking advantage of the bistable behavior.Rospendowiski, J.; Pinto, M. R.; Hessel, C.; Sitta, E.; Nagao, R. ACS Omega 2018, 3, 13636.

Interpretation of Gravity Monitoring Data on Geotechnical Impact on the Geological Environment

The Verkhnekamskoye potassium salt deposit located in the Perm Krai is the main source of raw materials for the potash industry in Russia. The penetration of underground waters into the shafts of the mine, which is situated beneath the industrial zone, and residential quarters of the city of Berezniki led to the flooding of the mine with subsequent collapsing of the earth’s surface. For obtaining the information about negative impacts of engineering processes associated with mineral mining operations, a method of highly accurate gravimetric monitoring observations is suggested, suitable for tracking the time changes of the gravitational field. As a result of monitoring observations we obtain a dynamic anomaly of gravity which is defined as the difference between the subsequent and the previous gravity values. Since all the unvarying components of the gravitational field are present in each pair of the observations, the dynamic anomaly only reflects a specific geological or mining process. The method for processing and interpretation of the dynamic anomalies of gravity, which synthesizes qualitative and quantitative approaches to extracting the geological information from gravity data, is developed. The interpretation yields the areal distribution and probable depth interval of the zone of rock decompaction and shows the magnitude of the change in the density of rocks characterizing the intensity of the decompaction process. The practical implementation of the highly accurate gravimetric monitoring observations is carried out in the emergency sites of the mines of the Verkhnekamskoye potassium salt deposit has demonstrated high efficiency of the suggested method.

A novel transient gravimetric monitoring technique implemented to GCL osmotic suction control

A modified osmotic suction control technique for monitoring apparent transient weight changes was successfully adapted to the wetting and drying paths of geosynthetic clay liners (GCLs). Reasonable control was possible, enabling suction equilibrium to be achieved without disruption to the test. The results provide unique insight into the time-dependent changes in water retention properties and the semi-permeable membrane behaviour of the bentonite component in GCLs. The stages of suction equilibrium, related to the tri-modal pore structure of GCLs and the point of capillary break, could also be monitored. While the osmotic method has been traditionally used to control matric suction (up to 10 MPa) in soils, the overall results presented in this paper indicate that its application for total suction control in GCLs is largely due to the membrane behaviour of their bentonite component. Furthermore, because of capillary break between the GCL and the osmotic solution at the water entry (or residual) suction value of a GCL, an upper limit of 2.8 MPa suction is recommended for the application of the osmotic method to measure the water retention properties of GCLs.

Numerical study of reservoir permeability effects on gravity changes associated with CO2 geological storage: implications for gravimetric monitoring feasibility

AbstractGravimetric methods are used for monitoring the migration of CO2 stored in the reservoir. Reservoir permeability is crucial for injectivity and potentially important for gravity changes associated with CO2 storage. Nevertheless, its effects on gravity changes have not been investigated systematically. After conducting numerical simulations of CO2 injection and storage using models with varying permeability conditions (50–1000 mD), we calculated surface gravity changes. Results show that two mechanisms affect gravity decrease, related to differences in CO2 density and in CO2 spatial patterns. Under low‐permeability conditions, gravity decrease is minimal during injection because of increases in pressure and the resulting relative high density of CO2. Gravity decrease is enhanced after injection ceases because of the pressure release and resulting CO2 expansion. These effects are strong at shallow depths, at which CO2 is near the critical point and highly compressible. Under higher permeability conditions, rapid spreading of the CO2 plume causes smaller gravity reduction rate after some decades of injection. After injection ceases, upward CO2 migration because of buoyancy and plume spreading increase gravity above the injection zone. The time required for gravity change detection depends on permeability. Detection during injection can be made earlier under higher permeability conditions and under lower permeability conditions after injection ceases. These points suggest that permeability affects the feasibility of gravimetric methods. Moreover, designing monitoring programs based on permeability and depth conditions is necessary for successful monitoring. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

Analyses of the Gravimetric and Electrochemical Effects of C16H13N3O3 on Mild Steel Corrosion in 0.5 M H2SO4

This study analyzed the gravimetric and electrochemical effects of C16H13N3O3 (methyl-5-benzoyl-2-benzimidazole carbamate: Mebendazole) on mild steel corrosion in 0.5 M H2SO4, for gaining insights on correlation and significance of differences between the two corrosion-monitoring techniques. For the gravimetric method, weight loss of mild steel specimens immersed in different C16H13N3O3 concentrations mixed in the 0.5 M H2SO4 were obtained for corrosion rates and inhibition efficiencies estimations. For the electrochemical approach, mild steel samples were subjected to potentiodynamic polarization experiments in the different C16H13N3O3 concentrations in 0.5 M H2SO4 that were employed for the gravimetric technique for obtaining instrumental readout of corrosion rate. Results showed that the corrosion rate from the electrochemical experiments exhibited excellent linear correlation (R = 99.91; Nash-Sutcliffe Efficiency = 99.83) with the dataset obtained from the gravimetric corrosion assessments. Both the gravimetric and electrochemical monitoring of mild steel corrosion gave inhibition efficiencies, η > 90%, by the different C16H13N3O3 concentrations for the study. Also, homeoscedastic and heteroscedastic student’s t-test statistics indicated that the differences between the corrosion inhibition efficiencies from the electrochemical and gravimetric techniques were not significant, p-value = 0.9729, but significant for their corrosion rates: 1.52 × 10–6 > p-value > 8.15 × 10–9.

Desarrollo de un material de referencia certificado para análisis elemental de agua potable

La producción de un material de referencia (MR) es un proceso en el que se realizan estudios relacionados con la preparación, envasado y caracterización (incluye homogeneidad y estabilidad). En este trabajo se presentan los resultados del desarrollo de un MR de agua potable. El envasado se realiza aplicando dos procedimientos (envasado convencional e inmersión). La caracterización se realizó por Absorción Atómica, ICPMS y Cromatografía iónica. La evaluación de homogeneidad del material se realizó para Na, Mg, Ca, Fe, K, Co, Pb, Mo, As, Ni, Se, Cu, Al, Cr Zn y aniones como NO3-y Cl-. La estabilidad se evaluó a corto (condiciones aceleradas) y largo plazo por ICPMS y CI, además se realizó seguimiento gravimétrico. La homogeneidad y estabilidad se evaluaron con base en su incertidumbre. La incertidumbre asociada a la homogeneidad y estabilidad MR evidenció resultados aceptables para la mayoría de los analitos. Los resultados del seguimiento gravimétrico permitieron detectar pérdidas de masa del material, por lo que se planteó un nuevo esquema para evaluar la estabilidad a través de métodos gravimétricos. Finalmente, se encontró que el MR presenta incertidumbres expandidas entre el 0,93% y el 4,38%, siendo apto para el uso previsto.

Tuning Electrochemical Bistability by Surface Area Blocking in the Cathodic Deposition of Copper.

We report herein a precise control of the electrochemical bistability induced by surface area changes during the cathodic deposition of copper. Small additions of 1,10-phenanthroline (Phen) in the reaction media present an inhibiting effect on the global rate mainly due to the adsorption of protonated Phen. The increase of its concentration favors a shrinkage of the bifurcation (saddle-node) diagram and shifts it to less negative potentials. The dynamic instability is verified by impedance measurements, and a negative impedance is clearly found. We calculated the apparent molar mass of the adsorbents using in situ gravimetric monitoring in the electrochemical experiments, and the results indicate that mass changes occur mainly due to the reduction of copper from bivalent ions dissolved in the reaction media. Importantly, the adsorption of protonated Phen molecules does not show a considerable contribution in mass variations but prevents the formation of a copper course grained morphology over the surface. Imaging analysis indicates finer nodulations at the lower branch compared to the upper branch in the bistability domain. On the basis of these observations, a kinetic mechanism is proposed and a good agreement is obtained between the apparent molar mass extracted from experiments and the theoretical values. Altogether, our results contribute to a detailed physical chemical description of the nonlinear behavior, bringing new insights about this reaction and pointing out the possibility to design switchable surface electrodes by taking advantage of the bistable behavior.

Integrating Moisture Characteristic Curves with Gravimetric Data in the Management of Substrate Moisture Content for Annual Vinca

Greenhouse growers must use water more efficiently. One way to achieve this goal is to monitor substrate moisture content to decrease leaching. A systems approach to irrigation management would include knowledge of substrate matric potentials and air-filled pore space (AS) in addition to substrate moisture content. To study the relationship between substrate moisture and plant growth, annual vinca (Catharanthus roseus L.) was subject to a 2 × 2 factorial combination of two irrigation treatments and two substrates with differing moisture characteristic curves (MCCs). A gravimetric on-demand irrigation system was used to return substrate moisture content to matric potentials of −2 or −10 kPa at each irrigation via injected drippers inserted into each container. Moisture characteristic curves were used to determine gravimetric water content (GWC), volumetric water content (VWC), and AS at target substrate matric potential values for a potting mix consisting of sphagnum moss and perlite and a potting mix consisting of sphagnum moss, pine bark, perlite, and vermiculite. At each irrigation event, irrigation automatically shut off when the substrate-specific weight of the potted plants associated with the target matric potential was reached. Irrigation was triggered when the associated weight for a given treatment dropped 10% from the target weight. VWC and AS differed between substrates at similar matric potential values. Irrigating substrates to −2 kPa increased the irrigation volume applied, evapotranspiration, plant size, leaf area, shoot and root dry weight, and flower number per plant relative to irrigating to −10 kPa. Fafard 3B had less AS than Sunshine LB2 at target matric potential values. Plants grown in Fafard 3B had greater leaf area, shoot dry weight, and root dry weight. Leachate fraction ranged from 0.05 to 0.08 and was similar across all treatment combinations. Using data from an MCC in conjunction with gravimetric monitoring of the container–substrate–plant system allowed AS to be determined in real time based on the current weight of the substrate. Closely managing substrate matric potential and AS in addition to substrate water content can reduce irrigation and leachate volume while maintaining plant quality and reducing the environmental impacts of greenhouse crop production.

Investigating the Trimethylaluminium/Water ALD Process on Mesoporous Silica by In Situ Gravimetric Monitoring.

A low amount of AlOx was successfully deposited on an unordered, mesoporous SiO2 powder using 1–3 ALD (Atomic Layer Deposition) cycles of trimethylaluminium and water. The process was realized in a self-built ALD setup featuring a microbalanceand a fixed particle bed. The reactor temperature was varied between 75, 120, and 200 °C. The self-limiting nature of the deposition was verified by in situ gravimetric monitoring for all temperatures. The coated material was further analyzed by nitrogen sorption, inductively coupled plasma-optical emission spectroscopy, powder X-ray diffraction, high-resolution transmission electron microscopy, attenuated total reflection Fourier transformed infrared spectroscopy, and elemental analysis. The obtained mass gains correspond to average growth between 0.81–1.10 Å/cycle depending on substrate temperature. In addition, the different mass gains during the half-cycles in combination with the analyzed aluminum content after one, two, and three cycles indicate a change in the preferred surface reaction of the trimethylaluminium molecule from a predominately two-ligand exchange with hydroxyl groups to more single-ligand exchange with increasing cycle number. Nitrogen sorption isotherms demonstrate (1) homogeneously coated mesopores, (2) a decrease in surface area, and (3) a reduction of the pore size. The experiment is successfully repeated in a scale-up using a ten times higher substrate batch size.

Milk and Its Sugar-Lactose: A Picture of Evaluation Methodologies

Lactose is the major disaccharide found in milk, and is catabolized into glucose and galactose by the enzyme lactase. Lactose is an important energy source and ssometimes it is referred to simply as milk sugar, as it is present in high percentages in dairy products. Lactose is the primary source of carbohydrates during mammal development, and represents 40% of the energy consumed during the nursing period. Lactose-intolerance individuals have a lactase deficiency; therefore, lactose is not completely catabolized. Lactose intolerance is a significant factor in the choice of diet for many sick people, therefore its content in foods must be monitored to avoid disorders and illnesses. This has created the need to develop simple methods, such as polarimetry, gravimetric, middle infrared, differential pH and enzymatic monitoring, but all these methods are time-consuming, because they required extensive sample preparation and cannot differentiate individual sugars. In order to quantify low levels of lactose, new and more accurate analytical methods have been developed. Generally, they require equipment such as HPLC or High Performance Anion Exchange with Pulsed Amperometric Detection (HPAE-PAD).