Continuous Properties Research Articles

Synthesis and characterization of β-cyclodextrin functionalized zeolite-A as biocompatible carrier for Levofloxacin drug; loading, release, cytotoxicity, and anti-inflammatory studies

β-cyclodextrin functionalized zeolite-A (β-CD/ZA) was synthesized and characterized as a potential carrier for Levofloxacin with enhanced loading, release, and anti-inflammatory properties. The LVC loading capacity of β-CD/ZA and zeolite-A is 363.4 ​mg/g and 244.7 ​mg/g respectively and this enhancement is related to the enrichment in the density of the active site after the functionalization process (Nm ​= ​160 ​mg/g (β-CD/ZA) and 104.6 ​mg/g (zeolite-A)). Based on the steric (n ​= ​2.26) and energetic (ΔE ​= ​−16.83 ​kJ/mol) parameters of the advanced equilibrium studies, the loading of LVC occurred as two or three ions per each active site by physical (<40 ​kJ/mol) and multimolecular mechanism in parallel orientation. The classic equilibrium investigation declared Pseudo-First order kinetic and Langmuir isotherm demonstrating homogenous and monolayer loading properties. Additionally, the thermodynamic investigation reflects the spontaneous and exothermic loading of LVC into β-CD/ZA. The LVC release profile of β-CD/ZA exhibits long, slow, and continuous release properties for 200 ​h. Based on the release kinetics results (Higuchi and Korsmeyer–Peppas), the LVC release process is controlled essentially by the diffusion mechanism and in addition to minor effects for the erosion mechanism. The LVC loaded β-CD/ZA particles exhibit enhanced anti-inflammatory properties against the production of cytokine (IL-6 and IL-8) within human bronchial epithelia cells (NL20).

A modified method for calculating the viscosity of multicomponent slags based on Kriging interpolation

Model prediction is an effective method to obtain the physicochemical properties data of molten slags, which is difficult to test experimentally due to their high melting points. Empirical models are prevalent at present; however, it needs large amount of experimental data to fit the empirical parameters with narrow application scope. In this paper, the Kriging interpolation method modified with oxide property weights, is firstly introduced into the viscosity prediction of multicomponent slags. The prediction results of CaO–Al2O3–SiO2, CaO–Al2O3–CaF2, CaO–Al2O3–SiO2–MgO and CaO–Al2O3–SiO2–MgO–CaF2 systems showed that the predicted errors by the Modified Kriging Interpolation (MKI) method are smaller than those by various empirical models. It is anticipated that the MKI method can be extended to predicting the continuous physicochemical properties of multicomponent slags.

A Posteriori Error Estimates of Edge Residual-Type of Weak Galerkin Mixed FEM Solving Second-Order Elliptic Problems on Polytopal Mesh

In this paper, we present a posteriori error estimator of edge residual-type Weak Galerkin mixed finite element method (WG-MFEM) solving second-order elliptic problems, where two different ways of a posteriori error estimator are presented, both of which hold on polygonal mesh. The two analyses are based on the standard FEM method and continuous local mass conservation property, respectively. In order to prove the reliability holding on polygonal meshes, the a posteriori error estimator is disposed by the post-processed numerical scalar solution. Compared with some other methods, the proposed a posteriori error estimator does not contain the post-processed solution and the efficiency can be obtained automatically. Numerical experiments are conducted to confirm the efficiency of this estimator.

Synthetic shelf sediment maps for the Greenland Sea and Barents Sea

Seabed sediment maps underpin a variety of marine research endeavours. Seabed mapping data are available for many regions, but these usually provide discrete classifications which obscure underlying continuous properties of the sediments. Other areas are poorly surveyed, e.g., polar regions which are inaccessible due to ice cover. Here, we focus on the inaccessible North East Greenland shelf for which there are almost no seabed sediment data. We trained a random forest model to predict sediment classes from an existing map of the well-surveyed neighbouring Barents Sea, using data on bathymetry, currents and waves. We then used our model to predict the unknown sediment distributions off East Greenland. In the process, we generated some new spatial data on previously un-mapped properties of the Barents Sea, such as mean grain size, organic carbon and nitrogen content, porosity and permeability. The maps of both regions are available to support future research activities in the Arctic, e.g., the parameterization of benthic biogeochemistry in ecosystem models, or mapping species distributions.

Continuous mixing process and properties of NR/CB nanocomposites based on elongational rheology

A self-developed biaxial eccentric rotor extruder (BERE) based on elongational rheology was adopted to prepare natural rubber (NR)/carbon black (CB) nanocomposites continuously through one-step process in 1.5 min. The micro morphology, rubber processing analysis, binding rubber content, relaxation time, molecular weight and distribution, vulcanization and mechanical properties of the prepared NR/CB nanocomposites were tested. By comparing with NR/CB nanocomposites prepared by internal mixer, it is proved that BERE continuous mixing process can not only greatly shorten the mixing time, reduce unit energy consumption, but also make the prepared NR/CB nanocomposites have good mixing and dispersion morphology, excellent physical and mechanical properties, high molecular weight retention and binding rubber content.

Correlation Between Yield Stress of Silty Mud Sediments and Continuous Oscillatory Shearing Properties

Correlation Between Yield Stress of Silty Mud Sediments and Continuous Oscillatory Shearing Properties

Rare-earth doped mixed sesquioxides for ultrafast lasers [Invited

Sesquioxides are outstanding host materials for rare-earth doped laser gain media. Unfortunately, their very high melting points make it challenging for them to be fabricated in high quality. Recently, we demonstrated that some mixed sesquioxides exhibit significantly reduced melting temperatures compared to their constituents. This enables their growth by the established Czochralski method yielding rare-earth doped mixed sesquioxides of high optical quality. Due to their inhomogeneously broadened gain spectra caused by the intrinsic disorder, mixed sesquioxides are very promising for the generation and amplification of ultrashort pulses. To envisage the potential of this emerging class of gain materials, this paper reviews the spectroscopic as well as continuous wave and pulsed laser properties of crystalline and ceramic rare-earth doped mixed cubic sesquioxides of the form (Scx,Luy,Yz)2O3 with x + y + z = 1.

A three-term CGPM-based algorithm without Lipschitz continuity for constrained nonlinear monotone equations with applications

In this work, a new three-term conjugate gradient projection method (CGPM) with a new adaptive line search strategy is proposed for solving the large-scale nonlinear monotone equations with convex constraints. The proposed three-term CGPM-based algorithm has the following characteristics: (i) its search direction satisfies the sufficient descent and trust region properties which is independent of the line search; (ii) the nonlinear equations only satisfy continuous and monotone properties; (iii) its global convergence is analyzed and obtained without the Lipschitz continuity. Some preliminary numerical experiment results are reported and their corresponding performance profiles are illustrated, which show that the proposed algorithm is effective. Finally, the proposed algorithm is extended to solve sparse signal restoration problems.

Global implicit function theorems and the online expectation–maximisation algorithm

SummaryThe expectation–maximisation (EM) algorithm framework is an important tool for statistical computation. Due to the changing nature of data, online and mini‐batch variants of EM and EM‐like algorithms have become increasingly popular. The consistency of the estimator sequences that are produced by these EM variants often rely on an assumption regarding the continuous differentiability of a parameter update function. In many cases, the parameter update function is not in closed form and may only be defined implicitly, which makes the verification of the continuous differentiability property difficult. We demonstrate how a global implicit function theorem can be used to verify such properties in the cases of finite mixtures of distributions in the exponential family, and more generally, when the component‐specific distributions admit data augmentation schemes, within the exponential family. We then illustrate the use of such a theorem in the cases of mixtures of beta distributions, gamma distributions, fully visible Boltzmann machines and Student distributions. Via numerical simulations, we provide empirical evidence towards the consistency of the online EM algorithm parameter estimates in such cases.

Mechanical properties and microstructural evolution of high-pressure torsion-processed Al7075 alloy at elevated temperatures

The severe plastic deformation of aluminum alloys can be advantageous for developing a unique microstructure by inducing dynamic recovery and dynamic precipitation. Because dynamic recovery and precipitation are related to temperature changes, an elevated temperature atmosphere during severe plastic deformation may accelerate microstructural changes in aluminum, resulting in different properties compared to that of the room-temperature processed sample. In the present work, the microstructural and mechanical properties of the elevated temperature high-pressure torsion-processed Al7075 alloy were investigated. Experimental results demonstrated that the elevated temperature during high-pressure torsion not only induces a dynamic recovery at a high shear strain regime but also yields coarse Mg, Zn, and Cu-rich precipitates in the aluminum matrix. Although the grain growth occurs from the shear strain of 7.8, evolved precipitates represents larger strength than matrix that result into continuous mechanical properties enhancement in the elevated temperature-processed sample. This result indicates that solute migration acceleration at an elevated temperature could be a suitable method to enhance the mechanical properties of aluminum alloys undergoing severe plastic deformation processing.

Assessing Overlapping Cloud Top Heights: An Extrapolation Method and Its Performance

Under the assumption that clouds are homogeneous and single-layered (SL), most current operational cloud top height (CTH) products derived from passive radiometers may largely underestimate the CTH of overlapping clouds. This article proposes a statistics-based extrapolation algorithm for retrieving the CTHs of overlapping clouds using only existing cloud property products available for most operational radiometers, and the method is successfully employed for the advanced himawari imager (AHI) observations. Because regional clouds within the same “system” have relatively continuous geometric properties, especially CTH, due to similar atmospheric conditions, upper-layer ice cloud CTHs (ITHs) and lower-layer water cloud CTHs (WTHs) are inferred using the CTH retrievals of well-chosen neighboring SL ice and water clouds, respectively. The proposed algorithm uses the latest machine-learning-based model to reasonably distinguish overlapping clouds from SL clouds, and optimizes the extrapolation by considering three physical constraints on neighboring, cloud phase, and cloud optical thickness (COT). Validated using active observations from CloudSat and cloud-aerosol Lidar and infrared pathfinder satellite observation (CALIPSO), our algorithm improves the AHI CTH mean bias for overlapping clouds from −5.1 to −2.6 km. More importantly, the algorithm provides CTH information of underlying water clouds that are unavailable from existing radiometer-based products. With the simultaneous retrieval of ITH and WTH, this algorithm increases our capability to detect the vertical structures of overlapping clouds and better evaluate the cloud radiative effects (CREs).

Decomposing Satellite-Based Classification Uncertainties in Large Earth Science Datasets

Collection of increasingly voluminous multispectral data from multiple instruments with high spatial resolution has posed both an opportunity and a challenge for maximizing their utilization, analysis, and impact. Obtaining accurate estimates of precipitation globally with high temporal resolution is crucial for assessing multiscale hydrologic impacts and providing a constraint for development of numerical models of the atmosphere that provide weather and climate predictions. Precipitation type classification plays an important role in constraining both the inverse problem in satellite precipitation retrievals and latent heat transfer within weather prediction simulations. Precipitation type, however, is often reported deterministically, without uncertainty attached to an estimate. Machine learning techniques are capable of extracting content of interest from large datasets and accurately retrieving discrete and continuous properties of physical systems, but with limited insights to the retrieval components—such as errors and the physical relationship between the observed and retrieved properties. To address this shortcoming, we perform precipitation type classification to introduce a novel tool for decomposing errors of satellite-retrieved products. We use Bayesian neural networks to map global precipitation measurement mission microwave imager observations to dual-frequency precipitation radar-derived precipitation type, which perform comparably to deterministic models, but with the added benefit of providing well-calibrated uncertainties. Through uncertainty decomposition, we demonstrate well-calibrated uncertainties as useful for making decisions concerning high uncertainty predictions, model selection, targeted data analysis, and data collection and processing. Additionally, our Bayesian models enable mathematical confirmation of a data distribution change as the cause for an unacceptable decline in model accuracy.

Coupled effects of temperature and compressive strain on aging of silicone rubber foam

The coupled effects of temperature and compressive strain on aging behaviors and mechanisms of silicone rubber foam were investigated by conducting the accelerated aging tests. The silicone rubber foams subjected to various levels of temperature and compressive strain were characterized by Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, micro hardness, volume fraction, compression set, continuous stress relaxation, mechanical properties, and thermogravimetric analysis (TGA) etc. The ATR-FTIR results indicate that the complex oxidation reactions (crosslinking, chain scission, and oxidation of side chains) occurred simultaneously with the formation of oxidation products. The high temperature facilitated the increase in crosslinking density and enhanced the thermal stability of the foams, implying that the oxidation crosslinking predominated over chain scission leading to the formation of a denser network structure. The physical and mechanical properties of the foams underwent significant changes due to the oxidation reactions and the irreversible collapse of the porous microstructure. The elevated temperature and the compressive stress both have a direct effect on the degradation of the foam. The elevated temperature played a more important role in changes of the physical-mechanical properties and microstructure.

Quantifying multipartite quantum entanglement in a semi-device-independent manner

We propose two semi-device-independent approaches that are able to quantify unknown multipartite quantum entanglement experimentally, where the only information that has to be known beforehand is quantum dimension, and the concept that plays a key role is nondegenerate Bell inequalities. Specifically, using the nondegeneracy of multipartite Bell inequalities, we obtain useful information on the purity of target quantum state. Combined with an estimate of the maximal overlap between the target state and pure product states, and a continuous property of the geometric measure of entanglement, we shall prove the information on purity allows us to give a lower bound for this entanglement measure. In addition, we show that a different combination of the above results also converts to a lower bound for the relative entropy of entanglement. As a demonstration, we apply our approach on 5-partite qubit systems with the Mermin-Ardehali-Belinskii-Klyshko (MABK) inequality, and show that useful lower bounds for the geometric measure of entanglement can be obtained if the Bell expression value is larger than 3.60, and those for the relative entropy of entanglement can be given if the Bell expression value is larger than 3.80, where the Tsirelson bound is 4.

Effect of copper-coated surfaces on the bacterial burden in the intensive care unit

Background: Pathogen-contaminated surfaces are known to transmit Healthcare-Associated Infections in hospitals and other healthcare facilities. Existing hospital-cleaning procedures alone are not enough to prevent the growth of microorganisms over time. Since copper alloy has inherent and continuous antibacterial properties, copper surfaces offer a solution to complement these procedures. Objectives: This study aimed to assess the antibacterial effects of copper-coated surfaces on the bacterial burden in the intensive care unit (ICU). Methods: This clinical controlled trial was conducted in a general ICU. The bacterial burden was measured on five surfaces that were coated with a copper alloy foil (purity 99.94%, 100-micron thickness) and five similar surfaces without the copper coating (n=60 each). The total bacterial burden and the colonization rate of Staphylococci, vancomycin-resistant enterococci, and gram-negative bacilli were measured on different surfaces. The collected data were analyzed using Chi-square or Fisher’s exact, Shapiro-Wilk, Mann-Whitney, and Kruskal-Wallis tests. Results: The cumulative bacterial burden was lower on copper-coated surfaces than on control surfaces. The copper-coated surfaces were found to have a significantly (95.96%) lower mean bacterial burden (145.20 colony-forming units [CFU]/100 cm2, n=60 surfaces) than the control surfaces (3,598.74 CFU/100 cm2, n=60 surfaces; P&lt;0.001). Conclusion: The results of this study showed that placing a copper coating on the surface of five common, highly touched objects in ICU rooms reduced the bacterial burden by 96%, as compared with control surfaces.

Complete Equation of State Thermal Formulation for Simulation of CO2 Storage

Summary Storage of carbon dioxide (CO2) in depleted gas reservoirs or large aquifers is one of the available solutions to reduce anthropogenic greenhouse gas emissions. Numerical modeling of these processes requires the use of large geological models with several orders of magnitude of variations in the porous media properties. Moreover, modeling the injection of highly concentrated and cold CO2 in large reservoirs with the correct physics introduces numerical challenges that conventional reservoir simulators cannot handle. We propose a thermal formulation based on a full equation of state (EoS) formalism to model pure CO2 and CO2 mixtures with the residual gas of depleted reservoirs. Most of the reservoir simulators model the phase equilibriums with a pressure-temperature-based formulation. With this usual framework, it is not possible to exhibit two phases with pure CO2 contents. Moreover, in this classical framework, the crossing of the phase envelope is associated with a large discontinuity in the enthalpy computation, which can prevent the convergence of the energy conservation equation. In this work, accurate and continuous phase properties are obtained, basing our formulation on enthalpy as a primary variable. We first implement a new phase-split algorithm with input variables as pressure and enthalpy instead of the usual pressure and temperature, and we validate it on several test cases. This algorithm can model situations in which the mixture can change rapidly from one phase to the other at constant pressure and temperature. Then, treating enthalpy instead of temperature as a primary variable in both the reservoir and the well modeling algorithms, our reservoir simulator can model situations with pure or near pure components, as well as crossing of the phase envelope that usual formulations implemented in reservoir simulators cannot handle. We first validate our new formulation against the usual formulation on a problem in which both formulations can correctly represent the physics. Then, we show situations in which the usual formulations fail to represent the correct physics and that are simulated well with our new formulation. Finally, we apply our new model for the simulation of pure and cold CO2 injection in a real depleted gas reservoir from the Netherlands.

High average output power from a backside-cooled 2-µm InGaSb VECSEL with full gain characterization.

We compare the gain and continuous wave lasing properties of two InGaSb-based vertical external cavity surface emitting lasers (InGaSb VECSEL) with different heat management approaches operating at a center wavelength of around 2μ m. To date, intracavity heatspreaders have been required for good average output power, which have many trade-offs, especially for passive modelocking. Here we demonstrate a record high average output power of 810 mW without an intracavity heatspreader using a backside-cooled non-resonant VECSEL chip optimized for modelocking. In addition, we introduce and demonstrate an optical characterization for a wavelength range of 1.9 to 3μ m to precisely measure wavelength-dependent gain saturation and spectral gain. Gain characteristics are measured as a function of wavelength, fluence, pump power and temperature. Small signal gain of more than 5%, small saturation fluences and broad gain bandwidths of more than 90 nm are demonstrated. In comparison to a commercial VECSEL chip with an intracavity heatspreader, we have obtained similar average output power even though our VECSEL chip is designed for antiresonance.

Insight into the Technical Qualification of the Sonocogreen CaO/Clinoptilolite Nanocomposite (CaO(NP)/Clino) as an Advanced Delivery System for 5-Fluorouracil: Equilibrium and Cytotoxicity.

Clinoptilolite as a natural zeolite was integrated with green CaO nanoparticles forming the green nanocomposite CaO(NP)/Clino. The CaO(NP)/Clino composite was assessed as a potential carrier for 5-fluorouracil (5-FL) drug. The CaO(NP)/Clino carrier achieved an enhanced 5-FL loading capacity of 305.3 mg/g as compared to 163 mg/g for pure clinoptilolite. The kinetics of the 5-FL loading follow the properties of the pseudo-first-order model, while the equilibrium results are related to the Langmuir isotherm. Therefore, the 5-FL loading processes occurred in the monolayer formed by homogeneous active loading receptors on the surface of the CaO(NP)/Clino carrier. The Gaussian energy of the 5-FL loading reaction (9.2 KJ/mol) reflected the dominant effect for the chemical mechanisms, especially the zeolitic ion-exchange mechanisms. Additionally, the thermodynamic parameters suggested endothermic, feasible, and spontaneous properties for the occurred 5-FL loading reactions. The release profile of 5-FL from CaO(NP)/Clino has continuous and long properties (150 h) at pH 1.2 (gastric fluid) and pH 7.4 (intestinal fluid). The kinetic studies of the release reactions show considerable agreement with Higuchi, Hixson–Crowell, and Korsmeyer–Peppas models. Such high fitting results and the diffusion exponent values (0.49 at pH 1.2 and 0.48 at pH 7.4) reflected the release properties of the Fickian transport behavior involving complex erosion and diffusion mechanisms. The cytotoxicity study of CaO(NP)/Clino on colorectal normal cells (CCD-18Co) declare the safe and biocompatible effect as a carrier for the 5-FL drug. Additionally, CaO(NP)/Clino as a carrier causes considerable enhancement for the cytotoxic effect of the loaded 5-FL drug on colon cancer cells (HCT-116).

Estimation and mapping of soil organic matter content at a national scale based on grid soil samples, a soil map and DEM data

Soil property maps at continental and national scales provide important input for research on biogeochemical and hydrological cycles. This paper develops a methodology for producing soil property maps at a continental or national scale based on soil samples from continental or national soil surveys (especially geochemical baseline surveys) with a 2–70 km grid, soil maps, and Digital Elevation Model data. The proposed method consists of four major steps: 1) determining the overall trend of soil property distribution using the linkage method; 2) estimating the variation inside each polygon through an extended Inverse Distance Weighted interpolation based on both the environmental similarity and spatial autocorrelation with stratification; 3) integrating variations in the soil property with its overall trend; 4) re-estimating soil properties in transition zones by using a weighted average of soil properties estimated from soil samples from different neighboring soils to produce a continuous soil property map across soil boundaries. A case study using Soil Organic Matter content as an example was conducted in Jilin Province (190,000 km2) in China based on soil samples from a 8–32 km grid from the China Soil Pollution Survey, the 1:1 million soil map of China and Shutter Radar Topographic Mission Digital Elevation Model data. Independent validation indicated that the proposed method decreased the mean error, the mean absolute error and the root mean square error by 10–30% compared with two commonly used soil mapping methods, the linkage method and Inverse Distance Weighted interpolation. The SOM map produced by the proposed method improved defects in the maps produced through Inverse Distance Weighted interpolation and the linkage method such as “bull's eye” patterns, abrupt change across soil boundaries and the ignored variation inside polygons on the maps. The proposed approach generates more accurate soil property maps at a continental or national scale based on grid soil samples from continental or national soil surveys than those produced through commonly used methods.

Coalescence inhibition and agglomeration initiation near the critical dilution of asphaltene precipitation

In bitumen recovery from oil sands, solvent addition is used to destabilize the water-in-diluted bitumen emulsions and separate the valuable oil product from water and solids. For each solvent, a critical solvent-to-bitumen ratio or critical dilution can be determined that coincides with the onset of bulk asphaltene precipitation, at which the system properties change abruptly. Above the critical dilution, solvent addition promotes bulk asphaltene precipitation and separation by the agglomeration of water droplets, solids and precipitated asphaltenes. Below the critical dilution, separation occurs by the coalescence of water droplets. The properties of the water-diluted bitumen interface could be key to improving the mechanistic understanding of water-in-diluted bitumen emulsions and bitumen recovery. In this work, we explore the behavior of water-in-diluted bitumen emulsions at macro- and microscopic scales, and provide novel insights at conditions below critical dilution. Bench scale bitumen froth treatment settling experiments highlight the possibility to attain effective water and solids separation based on agglomeration, without any noticeable bulk asphaltene precipitation. Light microscopy images reveal the inhibition of water droplet coalescence and the initiation of agglomeration due to the transformation of the oil continuous phase into a gel-like structure in the contact zone between water droplets. Thin liquid film observations show drastic changes in the continuous oil phase properties in the contact zone between water droplets at similar conditions that are attributed to the formation of both asphaltene aggregates at the interface and an oil gel-like structure that expands around them. These findings lead to the proposal that agglomeration can occur below critical dilution by surface asphaltene precipitation at the water-oil interface, without bulk asphaltene precipitation. The multiscale insights highlight opportunities to improve further not only bitumen froth treatment but also other oil-water-solids separation processes.