Changes In Surface Characteristics Research Articles

Preservation of Titanium in a Naringin-Containing Solution to Enhance Osteogenic and Anti-inflammatory Activities In Vitro

When exposed to air, the titanium implants undergo changes in surface characteristics and biological activity, which is known as biological aging. It is important to find a suitable storage method to slow down the biological aging of titanium. The purpose of this study was to develop a naringin-containing storage solution and evaluate the effects of this storage method on physicochemical properties as well as osteogenic and anti-inflammatory activities of commercial pure titanium (cp-Ti) and sandblasted with large grit and acid-etched titanium (SLA-Ti). Titanium surfaces stored in air and 0.9% NaCl solution for 4 weeks were served as control, and samples submerged in three different concentrations of naringin-containing solution for 4 weeks were used to investigate the new storage method. Surface topography images showed that nanostructures were observed on liquid-stored SLA-Ti surfaces. The storage condition did not influence the roughness of both cp-Ti and SLA-Ti. However, the wettability of titanium varied with the storage methods. Titanium stored in the naringin-containing solution exhibited lower contact angles. Samples stored in aqueous solution were less susceptible to hydrocarbon contamination. The preservation of titanium in the 10 μM naringin-containing solution enhanced the adhesion, proliferaton, and differentiation of osteoblasts. In addition, macrophages on samples stored in 10 μM and 100 μM naringin-containing solutions displayed better anti-inflammatory effect. In summary, the 10 μM naringin-containing solution could enhance osteogenic and anti-inflammatory activities of titanium and was proved to be an effective new storage condition.

Review: land, cloud, and climate change (in focus: Borneo)

This article discusses the salient findings of the Intergovernmental Panel on Climate Change Special Report on Climate Change and Land (2019). Local impacts of global warming in Borneo are discussed in terms of changes in temperature and precipitation. A drier and warmer climate is expected with the continued deforestation of Borneo. Changes in land surface characteristics of Borneo also affect the properties of cloud that forms over it. Deforested areas are generally associated with diffused clouds, small cloud particles, and thin and high clouds. Low vegetative areas are associated with a low evapotranspiration rate and low amount of latent heat release, which discourages the formation of convective clouds. The weak updraft associated with a non-convective cloud cannot support the formation of large cloud droplets. Moreover, the deforestation of primary forests of Borneo and replacing them with palm trees may cause larger cloud properties’ variability over the area.

Nanomaterials: An alternative source for biodegradation of toxic dyes

Environment contamination is a colossal worriment across the world, owing to its detrimental and negative impact on health and ecological systems. Dyes are one of the synthetic organic chemicals that are utilised in a variety of fields, including textiles. As a result, throughout one's production and subsequently in fibre colouring, these are becoming frequent industry-contributed contaminants. Increasing globalisation of international market has presented a problem to textile sector in terms of consistency and production. Textile processors' primary concern, as the highly competitive environment and environmental standards grow more severe is about being mindful of the grade of goods and even non-toxicity of their production processes. There seems to be an immediate necessity to look for methods and technologies which are useful in removing dye colours. Even though each has benefits and weaknesses, many physical, chemical, and biological approaches were explored and used with the application being dependent on the effluent properties, technical feasibility, and cost. Several remediation technologies are already developed, but they seem to be ineffective at removing dyes completely. There is a fast growth of nanoparticles applications in the past few years which has opened up newer, innovating, highly efficient, and low-cost dyes remediation systems. Nanomaterials with large surface areas change surface characteristics and distinctive electron conducting capabilities which make them ideal candidate for the treatment of wastewater that contains dyes. In this review, we have highlighted not only the role of nanotechnology in dye remediation processes but also different types of nanomaterials that can be used for the remediation of dyes.

Investigation of Electrochemical Dissolution Behavior of Near-α TA15 Titanium Alloy in NaCl Solution with Low-Frequency Pulse Current

TA15 material is a typical near-α titanium alloy and widely used for the aircraft key load bearing components. Electrochemical machining (ECM) is a cost-effective method to machine difficult-to-cut TA15. Due to the high chemical reactivity of titanium, titanium alloy is prone to passivation, which increases the difficulty of ECM, especially for some common ECM methods with low-frequency pulse currents. To investigate the change of surface characteristics of titanium alloy in pulse ECM, the dissolution behavior of TA15 in NaCl solution under the low frequency pulse current was analyzed by scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). The results showed that even after removal of initial air-formed oxide film, TA15 would be passivated to form a new passive film during long pulse-off time. Under short pulse-on time, the passive film formed in pulse-off time could not be effectively removed in one pulse-on time, and the passivation effect would be accumulated, resulting in poor machined surface with humps and pits. When the pulse-on time was long enough to completely remove the newly formed passive film, TA15 was dissolved normally to obtain excellent surface with clear crystal structure.

Coagulation Behavior of Antimony Oxyanions in Water: Influence of pH, Inorganic and Organic Matter on the Physicochemical Characteristics of Iron Precipitates.

The presence of inorganic and organic substances may alter the physicochemical properties of iron (Fe) salt precipitates, thereby stabilizing the antimony (Sb) oxyanions in potable water during the chemical treatment process. Therefore, the present study aimed to examine the surface characteristics, size of Fe flocs and coagulation performance of Sb oxyanions under different aqueous matrices. The results showed that surface properties of Fe flocs significantly varies with pH in both Sb(III, V) suspensions, thereby increasing the mobility of Sb(V) ions in alkaline conditions. The negligible change in surface characteristics of Fe flocs was observed in pure water and Sb(III, V) suspension at pH 7. The key role of Van der Waals forces of attraction as well as hydration force in the aggregation of early formed flocs were found, with greater agglomeration capability at higher more ferric chloride dosage. The higher Sb(V) loading decreased the size of Fe flocs and reversed the surface charge of precipitates, resulting in a significant reduction in Sb(V) removal efficiency. The competitive inhibition effect on Sb(III, V) removal was noticed in the presence of phosphate anions, owing to lowering of ζ-potential values towards more negative trajectory. The presence of hydrophobic organic matter (humic acid) significantly altered the surface characteristics of Fe flocs, thereby affecting the coagulation behavior of Sb in water as compared to the hydrophilic (salicylic acid). Overall, the findings of this research may provide a new insight into the variation in physicochemical characteristics of Fe flocs and Sb removal behavior in the presence of inorganic and organic compounds during the drinking water treatment process.

Effects of Chemical Cleaning on the Ageing of Polyvinylidene Fluoride Microfiltration and Ultrafiltration Membranes Fouled with Organic and Inorganic Matter.

Herein, the effects of cleaning with sodium hydroxide and citric acid solutions as cleaning reagents on the changes in the properties of two hollow-fiber PVDF microfiltration (MF) and ultrafiltration (UF) membranes fouled with organic and inorganic matter were investigated. Accelerated membrane ageing was induced by use of high concentrations of tannic acid and iron oxide (Fe2O3) particles in the feed water; these conditions were kept with different membrane soaking times to observe temporal effects. It was found that tannic acid molecules adsorb onto the membrane surface that results in changes in surface characteristics, particularly surface functional groups that are responsible for enhancing membrane’s hydrophilicity. Experimental results demonstrate that NaOH had a stronger effect on the tensile strength and surface chemistry of the fouled MF and UF membranes than citric acid. Prediction of lifetime by an exponential (decay) model confirmed that the UF membrane cleaned with NaOH would be aged within about 1.8 years and the MF membrane after about 5 years, at cleaning every 15 days, downtime 2 h per cleaning, when a 10% tensile strength decrease against the original membrane is allowed.

Albedo Parametrizations for the Laohugou Glacier No.12 in the Qilian Mountains—Previous Models and an Alternative Approach

Accurate estimates of albedo can be crucial for energy balance models of glaciers. A number of algorithms exist which are often site dependent and rely on accurate measurements or estimates of snow depth. Using the well-established COSIMA model we simulate the energy and mass balance of the Laohugou Glacier No.12 in the Qilian Mountains, on the northern fringe of the Qinghai-Tibetan Plateau, a glacier that has been well studied in the past. Using energy flux and mass balance measurements between 2010 and 2015 we were able to validate the model over multiple seasons. Using the original albedo parametrization, the model fails to reproduce the observed mass balance. We show that this is due to the failure to estimate snow depth accurately. We therefore applied two alternative albedo algorithms, one well established example and one new parametrization only dependent on temperature and time since last snow fall. As a result, mass balance simulations improve considerably from a RMSE of 0.53 m w.e. for the original parametrization to 0.39 and 0.19 m w.e. for the uncalibrated established and the new calibrated model respectively. Modelled albedo during the ablation period (NSE = 0.05, R2 = 0.33) is more accurate than during the accumulation period (NSE = −0.37, R2 = 0.04). Testing the new model at another glacier on the Tibetan Plateau shows that a local recalibration of parameters remains necessary to achieve satisfying results. Investigations into the effect of impurities in snow, regional moisture sources and changing surface characteristics with rising temperatures will be crucial for accurate projections into the future.

Investigation on the relationship between the surface texture index and the surface free energy of aggregate

The surface free energy (SFE) of aggregate and asphalt binder can be utilized to quantify the adhesion between the aggregate and binder. The SFE value varies with the changing surface characteristics. This study investigated the effect of surface texture on the aggregate’s SFE when applying the contact angle measurement. A surface treatment protocol for granite, diabase, basalt, and limestone was designed. A dicing saw, grinder and abrasive paper were utilized and were combined into three groups to treat the aggregates’ surface — Groups A, B, and C. The group in which aggregate was not treated was labeled Group D. The aggregate image measurement system (AIMS) was employed to quantify the surface characteristic. After surface treating, four levels of surface texture index were obtained. The surface texture indexes of the treated aggregates followed an increasing rank: A < B < C < D. A higher surface texture index indicated higher surface roughness. Subsequently, the sessile drop method was utilized to measure the contact angle and obtain the SFE of the aggregates that been treated through Groups A, B, and C. The gas adsorption method was applied to determine the SFE of aggregates in Group D. With the increasing surface texture index, the contact angle also increased and resulted in an increasing SFE value. An exponential-type model was established to describe the relationship between surface texture index and SFE. The model was first employed to fit the SFE data of aggregates in the A, B, C, and D groups, which showed good satisfaction of model fitting. The model was also applied to fit the SFE data of aggregates in the A, B, and C groups and to predict the SFE values based on the surface texture index obtained in Group D, which indicated good predictability. The fitting parameters showed a variable coefficient within 20% in the two fitting methods, which confirmed the model was reliable.

The response of bioactive titanium surfaces with different structure to UVC-irradiation to eliminate the negative effect on biological properties during aging time

The biological aging of titanium implants affects the service lifetime negatively in clinical applications, and Ultraviolet (UV) irradiation is an applicable method to overcome the biological aging. This study investigated the changes in surface characteristics and biological properties of bioactive titanium surfaces with different structure and topography after Ultraviolet C (UVC) irradiation. The bioactive titanium surfaces were prepared by anodizing (AO), sandblasting and acid-etching (SLA), acid-alkali etching (AA), alkali-heat etching (AH) methods. Samples were stored at dark for 7 weeks to simulate biological aging process and then irradiated by UVC for 2 h. The results showed that the hydroxyl groups (Ti-OH) on surfaces, which are crucial to enhance the biological properties, were easier to be generated on AO surfaces by UVC-irradiation, owing to a mixture of anatase and rutile on surfaces. UVC-irradiation had the strongest effect on AO surfaces to enhance the bioactivity in bone-like apatite deposition and better biocompatibility in mesenchymal stem cells (MSCs) attachment and proliferation. Therefore, titanium surfaces with a mixture phase of anatase and rutile have the potential to effectively utilize the benefits of UVC-irradiation to overcome the negative effects of the biological aging and have a promising clinical application prospect.

Modeling bulk surface resistance and evaluation of evapotranspiration using remote sensing and MATLAB

Abstract In developing countries, computation of actual evapotranspiration (AET) is challenging due to the lack of ground-based flux measurement data. The estimation of AET is crucial for water resources management involving the allocation of water for different land use/land cover (LULC) classes. The study's novelty was mapping pixel-by-pixel spatial variations of bulk surface resistance and evaluating the derived actual evapotranspiration in a sub-humid tropical river basin where flux tower data was lacking for validation. This study aimed to map bulk surface resistance and evaluate the estimated AET by global evapotranspiration data product (MOD16A2). Moderate Resolution Imaging Spectroradiometer (MODIS) data products, including land surface reflectance (LSR), land surface temperature (LST) and leaf area index (LAI) data, were used as input in MATLAB for mapping pixel-wise variations to analyze the seasonal variations in bulk surface resistance (rs) and AET in pre-monsoon and post-monsoon seasons during the years 2019 and 2012. The years 2019 and 2012 were selected because 2019 experienced a relatively wet pre-monsoon and post-monsoon, whereas 2012 experienced the opposite conditions, which proved useful when interpreting variations that are influenced by wetness conditions. Overall, the results indicated significant variability in the rs and AET for different LULC classes. MOD16A2 AET was determined to be slightly higher than the LULC classes' estimated AET. This study's MODIS satellite data products provided information on surface characteristics at a reasonable resolution. This permitted the identification of differences in LULC classes and changes in surface characteristics by season and wetness conditions, which are helpful when estimating AET.

Sub-field of view surface thermal modeling of Cassini CIRS observations of Rhea during south polar winter

Rhea's exosphere is thought to originate from sources of carbon, water ice and other volatiles that arrived at Rhea by bombardment. Its seasonal variability is directly driven by polar surface temperatures allowing surface adsorption, and the persistence of source volatiles require that seasonal temperatures remain sufficiently cold to retain them. Cassini CIRS detected temperatures in Rhea's winter polar region of 23 K, amongst the coldest measured in the Solar System, but with a relatively large footprint we seek to add value to these observations by modeling sub field-of-view (FOV) temperature distribution and examining how the coldest scenes evolve on a seasonal basis.A simple, rough surface 1-dimensional thermal model is developed using a digital elevation map as input to a thermal model. We compared averaged rough and flat modeled FOVs to CIRS temperatures for a set of case study observations in the south polar region in winter darkness and found they both agree within expected CIRS error in all cases. We develop an asymmetric estimate of CIRS FOV temperature uncertainty, which is particularly important for very cold spectra to accurately represent the sensitivity of the instrument. This approach provides a conservative upper temperature limit to spectral fits whilst highlighting there is often little information to constrain the lower bound of temperature uncertainty in these cases.The distribution of modeled sub-FOV facet temperatures is explored for the full range of azimuth angles and slope gradients. More extensive and cooler temperatures were found in the rough model, complemented by fewer but warmer areas than the flat model. We find temperature contrasts of individual model facets of up to 15 K warmer and 11 K colder within some CIRS FOV when the rough model was compared flat, in a case study of scenes in winter darkness. This is due to the persistence of the seasonal thermal wave beneath the surface. We tested model sensitivity to thermal input parameters (thermal inertia and bolometric Bond albedo). These values are challenging to constrain due to limited observations and measurement noise and are expected to vary with subtle changes in surface characteristics. We found that within 20° of the pole, temperatures do not rise significantly above 80 K all year, implying that a variety of simple organic molecules, linear amides and other carbon-containing compounds would remain stable on a quasi-permanent basis, potentially until photolytic or radiolytic mechanisms liberate by-products which provide a source for exospheric constituents. The simple rough model indicates that some facets experience very different summer/winter season lengths than a flat model can represent, which is important in terms of the exospheric sequestration process.We use threshold temperatures of 55 K for CO2 and 30 K for O2 ice as proxies for their relative stability at the surface. The surface coverage of these temperatures with time was compared to modeled exospheric abundance by Teolis and Waite (2016). They are anti-correlated which is expected, but with slight differences in timings of minima and the equinoctial maxima. We find that the rough model suggests larger areas able to adsorb these species than the flat model, and that the cumulative influence of topography would have a direct relationship on the timing and abundance of the exosphere.We place Rhea's polar environment in context with other icy moons in the Saturnian system using the flat model. The satellites Tethys, Dione and Enceladus experience similar polar thermal regimes to Rhea (with exceptionally cold winters) and would potentially benefit from the consideration of topography in relation to exospheric modeling.

Colour-stability analysis for estimation of deterioration in concrete due to chemical attack

Inaccessibility and subjectivity in damage evaluation during visual inspection may often lead to faulty assessment of concrete. Digital imaging tools can be used to identify and quantify the extent of distress due to deteriorating agents on concrete. Structures subjected to environmental degradation manifest deterioration in terms of changes in surface characteristics. It is strongly believed that there lies a co-dependency between the extent of deterioration and the reduction in the mechanical and durability performance. In the present study, digital image analysis technique, namely Colour-Stability Analysis (CSA), has been performed on cube samples of 30 MPa grade concrete, immersed in acid solutions (HCl, H2SO4), chloride (NaCl) and sulphate (MgSO4) at 5% concentration, exposed for various periods of 3, 7, 14 and 28 days, after the end of the requisite 28-day curing period. The CSA is conducted in CIE-LAB colour space as it is device-independent and represents the human perception of colour. The colour profiles of the deteriorated surfaces before and after immersion in the above reagents for 3, 7, 14 and 28 days have been quantified. The successive and relative differences in the surface colour profiles for respective reagent-immersion and exposure conditions have been computed and analysed. The current study revealed the influence and mechanism of various reagent’s impact on the deterioration of concrete surface with time and the same is quantified. The correlation between the extent of damage in concrete in terms of change in colour profiles, residual strength and durability is established.

An in vitro comparative evaluation of casein phosphopeptide-amorphous calcium phosphate fluoride, tricalcium phosphate and grape seed extract on remineralization of artificial caries lesion in primary enamel.

To evaluate and compare the remineralization potential of casein phosphopeptide-amorphous calcium phosphate fluoride, tricalcium phosphate and grape seed extract on artificial caries lesions in primary enamel. A sample of 40 non-carious, primary molar teeth was collected and cut in longitudinal sections into three equal halves. Those 120 samples were divided into four equal groups. Group A: Sections treated with casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF), Group B: Sections treated with tricalcium phosphate, Group C: Sections treated with grape seed extract Group D: Sections treated with deionized water (control group). Samples were evaluated for change in surface characteristics, mineral content using Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and microhardness using Vicker's microhardness tester. Cavitated lesions were evaluated for Cone beam computer tomography to obtain baseline data post remineralization. The remineralization potential of grape seed extract was found to be greater compared to tricalcium phosphate followed by CPP-ACPF. All the three groups viz. CPP-ACPF, tricalcium phosphate and grape seed extract showed remineralization under the in vitro pH cycling model, while grape seed extract group showed significantly greater remineralization compared to the CPP-ACPF and tricalcium phosphate groups.

Changes in Surface Characteristics of BOPP Foil after Treatment by Ambient Air Plasma Generated by Coplanar and Volume Dielectric Barrier Discharge.

Biaxially oriented polypropylene (BOPP) is a highly transparent polymer defined by excellent mechanical and barrier properties applicable in the food packaging industry. However, its low surface free energy restricts its use in many industrial processes and needs to be improved. The presented study modifies a BOPP surface using two different atmospheric-pressure plasma sources operating in ambient air and capable of inline processing. The volume dielectric barrier discharge (VDBD) and diffuse coplanar surface barrier discharge (DCSBD) were applied to improve the wettability and adhesion of the 1–10 s treated surface. The changes in morphology and surface chemistry were analyzed by SEM, AFM, WCA/SFE, and XPS, and adhesion was evaluated by a peel force test. Comparing both plasma sources revealed their similar effect on surface wettability and incorporation of polar functional groups. Additionally, higher surface roughness in the case of VDBD treatment contributed to slightly more efficient adhesion in comparison to DCSBD. Although we achieved comparable results for both plasma sources in the term of enhanced surface wettability, degree of oxidation, and stability of induced changes, DCSBD had less effect on the surface deterioration than VDBD, where surface structuring caused an undesirable haze.

Effects of remote ischemic preconditioning (RIPC) and chronic remote ischemic preconditioning (cRIPC) on levels of plasma cytokines, cell surface characteristics of monocytes and in-vitro angiogenesis: a pilot study

Remote ischemic preconditioning (RIPC) protects the heart against myocardial ischemia/reperfusion (I/R) injury and recent work also suggested chronic remote ischemic conditioning (cRIPC) for cardiovascular protection. Based on current knowledge that systemic immunomodulatory effects of RIPC and the anti-inflammatory capacity of monocytes might be involved in cardiovascular protection, the aim of our study was to evaluate whether RIPC/cRIPC blood plasma is able to induce in-vitro angiogenesis, identify responsible factors and evaluate the effects of RIPC/cRIPC on cell surface characteristics of circulating monocytes. Eleven healthy volunteers were subjected to RIPC/cRIPC using a blood pressure cuff inflated to > 200 mmHg for 3 × 5 min on the upper arm. Plasma and peripheral blood monocytes were isolated before RIPC (Control), after 1 × RIPC (RIPC) and at the end of 1 week of daily RIPC (cRIPC) treatment. Plasma concentrations of potentially pro-angiogenic humoral factors (CXCL5, Growth hormone, IGFBP3, IL-1α, IL-6, Angiopoietin 2, VEGF, PECAM-1, sTie-2, IL-8, MCSF) were measured using custom made multiplex ELISA systems. Tube formation assays for evaluation of in-vitro angiogenesis were performed with donor plasma, monocyte conditioned culture media as well as IL-1α, CXCL5 and Growth hormone. The presence of CD14, CD16, Tie-2 and CCR2 was analyzed on monocytes by flow cytometry. Employing in-vitro tube formation assays, several parameters of angiogenesis were significantly increased by cRIPC plasma (number of nodes, P < 0.05; number of master junctions, P < 0.05; number of segments, P < 0.05) but were not influenced by culture medium from RIPC/cRIPC treated monocytes. While RIPC/cRIPC treatment did not lead to significant changes of the median plasma concentrations of any of the selected potentially pro-angiogenic humoral factors, in-depth analysis of the individual subjects revealed differences in plasma levels of IL-1α, CXCL5 and Growth hormone after RIPC/cRIPC treatment in some of the volunteers. Nevertheless, the positive effects of RIPC/cRIPC plasma on in-vitro angiogenesis could not be mimicked by the addition of the respective humoral factors alone or in combination. While monocyte conditioned culture media did not affect in-vitro tube formation, flow cytometry analyses of circulating monocytes revealed a significant increase in the number of Tie-2 positive and a decrease of CCR2 positive monocytes after RIPC/cRIPC (Tie-2: cRIPC, P < 0.05; CCR2: RIPC P < 0.01). Cardiovascular protection may be mediated by RIPC and cRIPC via a regulation of plasma cytokines as well as changes in cell surface characteristics of monocytes (e.g. Tie-2). Our results suggest that a combination of humoral and cellular factors could be responsible for the RIPC/cRIPC mediated effects and that interindividual variations seem to play a considerable part in the RIPC/cRIPC associated mechanisms.

Soil erodibility indicators as affected by water level fluctuations in the Three Gorges Reservoir area, China

The near soil surface characteristics of plant communities probably change considerably with seasonal water-level fluctuations, thus induced corresponding variations in soil erodibility indicators. This study was conducted to investigate the variations in soil erodibility indicators triggered by varying inundation intensity or temporal water-level fluctuations in the Three Gorges Reservoir area. Two non-inundation sites (as the control) and six sites with different water-level fluctuation intensities were selected to measure or calculate eight soil erodibility indicators and then to determine a comprehensive soil erodibility index (CSEI). The erodibility indicators included K factor, slaking rate (SR), mean weighted diameter of aggregates (MWD), mean number of waterdrop impacts (MND), structural stability index (SSI), saturated conductivity (Ks), cohesion (Coh), and penetration resistance (PR). The variation in each soil erodibility indicator could be explained by the changes in near soil surface characteristics of plant community. The results indicated that the MWD, MND, SR, Coh, SSI, and Ks decreased gradually with the intensity of water level fluctuations (IWLFs), while the reverse was found for PR. K factor firstly increased and then decreased with the IWLFs. The CSEI increased with IWLFs, which was closely related to elevation. Compared with the control, CSEI increased by 123.3%, 132.9%, 93.9%, 84.8%, 48.7%, and 55.2% for water levels of 150, 155, 160, 165, 170 and 175 m, respectively. The changes in near soil surface characteristics of the plant community directly led to differences in soil erodibility indicators. Significant positive correlations were detected between soil erodibility indices, and bulk density and sand content, while significant negative correlations were found between root mass density, silt, clay, and organic matter contents. CSEI increased linearly with inundation time and duration. The results are helpful for understanding the mechanism of seasonal fluctuations in soil erodibility for land frequently inundated by water.

Overcoming the Challenges of Thermal Infrared Orthomosaics Using a Swath-Based Approach to Correct for Dynamic Temperature and Wind Effects

The miniaturization of thermal infrared sensors suitable for integration with unmanned aerial vehicles (UAVs) has provided new opportunities to observe surface temperature at ultra-high spatial and temporal resolutions. In parallel, there has been a rapid development of software capable of streamlining the generation of orthomosaics. However, these approaches were developed to process optical and multi-spectral image data and were not designed to account for the often rapidly changing surface characteristics inherent in the collection and processing of thermal data. Although radiometric calibration and shutter correction of uncooled sensors have improved, the processing of thermal image data remains difficult due to (1) vignetting effects on the uncooled microbolometer focal plane array; (2) inconsistencies between images relative to in-flight effects (wind-speed and direction); (3) unsuitable methods for thermal infrared orthomosaic generation. Here, we use thermal infrared UAV data collected with a FLIR-based TeAx camera over an agricultural field at different times of the day to assess inconsistencies in orthophotos and their impact on UAV-based thermal infrared orthomosaics. Depending on the wind direction and speed, we found a significant difference in UAV-based surface temperature (up to 2 °C) within overlapping areas of neighboring flight lines, with orthophotos collected with tail wind being systematically cooler than those with head wind. To address these issues, we introduce a new swath-based mosaicking approach, which was compared to three standard blending modes for orthomosaic generation. The swath-based mosaicking approach improves the ability to identify rapid changes of surface temperature during data acquisition, corrects for the influence of flight direction relative to the wind orientation, and provides uncertainty (pixel-based standard deviation) maps to accompany the orthomosaic of surface temperature. It also produced more accurate temperature retrievals than the other three standard orthomosaicking methods, with a root mean square error of 1.2 °C when assessed against in situ measurements. As importantly, our findings demonstrate that thermal infrared data require appropriate processing to reduce inconsistencies between observations, and thus, improve the accuracy and utility of orthomosaics.

Surface tension measurement of Nd − Fe − B − X melts (X = O, Cu, Ga, In) as simulated substances of Nd-rich phase in Nd magnet

The microstructure of a neodymium (Nd)- iron (Fe)- boron (B) sintered magnet must be appropriately controlled in the sintering and annealing processes to improve the performance of the Nd magnet. In this study, the surface tension of molten Nd alloys containing copper (Cu), gallium (Ga), or indium (In) as a simulated substance of the Nd-rich phase was measured to investigate the formation mechanism of the microstructure from the perspective of physicochemical properties of the Nd-rich phase. The surface tension of the molten Nd–Fe alloy at the liquidus gradually decreased with an increase in Nd concentration, accompanied by a decrease in temperature. This indicates that lower temperatures are advantageous for the wetting-infiltration of the liquid Nd-rich phase into the interspace between the Nd2Fe14B grains in the magnet. While considering the dependence of the surface tension of the Nd–Fe–B ternary eutectic on the oxygen (O) concentration, no significant difference in the surface tension was determined in the investigated range of O concentrations (600–3000 mass ppm O). The surface tension of the ternary eutectic alloy did not significantly change with the substitution by Cu, which implies that the change in surface characteristics due to the addition of Cu is not the primary reason for the improvement in wetting of the Nd-rich phase. The surface tension of the ternary eutectic alloy increased with the substitution by Ga, but decreased with the substitution by In.

A 3-dimensional prediction model for mechanical strength of basalt-steel fiber-reinforced recycled aggregate concrete based on reaction surface method

The application of fibers being used to Reinforce recycled aggregate concrete (RAC) has received continuous attention in recent years. However, the effect of variation in fiber dose on the basic mechanical properties of RAC has not been carefully distinguished in studies of hybrid fiber reinforced RAC. In the present study, the response surface method was applied to the strength study of the basic mechanical properties of hybrid fiber-reinforced RAC, with emphasis on obtaining the surface morphology of the strength change with fiber incorporation. Microscopic images were applied to detect the changes in surface characteristics of the fragments of fiber-reinforced RAC specimens after stressing, and the mechanism of the basic properties of hybrid fiber-reinforced RAC was revealed in combination with the damage morphology of macroscopic specimens. A three-dimensional prediction model of the mechanical strength of fiber RAC was derived from the surface morphology, and the variation of fiber admixture was extended from a single point to a range, and the effect of two different fiber admixtures on the mechanical strength of RAC was analyzed regionally, which enriched the research method of hybrid fiber-reinforced concrete.

A systematic assessment of water vapor products in the Arctic: from instantaneous measurements to monthly means

Abstract. Water vapor is an important component in the water and energy cycle of the Arctic. Especially in light of Arctic amplification, changes in water vapor are of high interest but are difficult to observe due to the data sparsity of the region. The ACLOUD/PASCAL campaigns performed in May/June 2017 in the Arctic North Atlantic sector offers the opportunity to investigate the quality of various satellite and reanalysis products. Compared to reference measurements at R/V Polarstern frozen into the ice (around 82∘ N, 10∘ E) and at Ny-Ålesund, the integrated water vapor (IWV) from Infrared Atmospheric Sounding Interferometer (IASI) L2PPFv6 shows the best performance among all satellite products. Using all radiosonde stations within the region indicates some differences that might relate to different radiosonde types used. Atmospheric river events can cause rapid IWV changes by more than a factor of 2 in the Arctic. Despite the relatively dense sampling by polar-orbiting satellites, daily means can deviate by up to 50 % due to strong spatio-temporal IWV variability. For monthly mean values, this weather-induced variability cancels out, but systematic differences dominate, which particularly appear over different surface types, e.g., ocean and sea ice. In the data-sparse central Arctic north of 84∘ N, strong differences of 30 % in IWV monthly means between satellite products occur in the month of June, which likely result from the difficulties in considering the complex and changing surface characteristics of the melting ice within the retrieval algorithms. There is hope that the detailed surface characterization performed as part of the recently finished Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) will foster the improvement of future retrieval algorithms.