Sigmoidal Model Research Articles

Effect of extrusion parameters on the interaction between rice starch and glutelin in the preparation of reconstituted rice

Reconstituted rice produced by extrusion has been attracted attention due to nutritional fortification and convenient production. Nevertheless, how to achieve desirable qualities and physicochemical properties of reconstituted rice nearly to natural rice by regulating extrusion process parameters is difficult. Herein, rice starch/glutelin mixture as raw material of reconstituted rice was extruded at varying extrusion conditions. Specific mechanical energy (SME) and sectional expansion index (SEI) dropped with rise in density (R2 = 0.9117 and 0.8207). Solubility was enhanced with increase in product temperature (R2 = 0.9085), color darkened and shifted to reddish and yellowish as extrusion temperature increased (R2 = 0.8577). These trends were well fitted by sigmoid models. Furthermore, SME enhanced hydrophobic and electrostatic interactions between rice starch and glutelin and caused the reduction in crystallinity and thermal stability, promoting the formation of a bi-continuous matrix of protein aggregates with rice starch. The obtained results can be applied to guide the production of reconstituted rice with desirable qualities.

The Polish Provenances of European Larch Overperform the Expected Growth Dynamics Indicated by the Sigmoid Model

This article attempts an unusual interpretation of the observations characteristic of experiments that compare different tree species’ provenances. The focus falls on larch (Larix decidua subsp. polonica). The data came from the experiment established in 1967 at the Siemianice forest experimental station, where 21 Polish larch provenances were compared. The study’s main objective was to compare the basic estimates of growth dynamics, the maximum growth rate and acceleration, and the point in time when these values were achieved. A four-parameter sigmoid growth function was used to model the average stand basal area increments and its first and second derivatives to calculate the indicators of the growth dynamic. The models explained 98% of the observed variations resulting from the 21 inventories. Only one growth parameter showed a statistically significant difference among the compared provenances. The Góra Chełmowa provenance achieved the highest value of the maximum growth acceleration, but it was statistically significantly different only from the three underperformed provenances. However, when the average values for all the experimental plots (n = 86) were compared with those of the deterministic model (the stand volume and yield tables), the maximum growth rate and acceleration values were higher for the former. We discuss the potential factors responsible for this overperformance and point out the potential risks that arise from growth and quality metrics only when deciding on the best-performing provenances. The sigmoid growth model employed in this study might be an excellent alternative for comparing the growth dynamics among different stands or replications in experimental studies. Considering only the early results, the sigmoid growth model proves its limitations, and the conclusions reached should be treated with caution.

Population total and unbound pharmacokinetics and pharmacodynamics of ciprofol and M4 in subjects with various renal functions.

The aim of this study was to develop a population pharmacokinetic (PK) model to simultaneously describe both total and unbound concentrations of ciprofol and its major glucuronide metabolite, M4, and to link it to the population pharmacodynamics (PD) model in subjects with various renal functions. A total of 401 and 459 pairs of total and unbound plasma concentrations of ciprofol and M4, respectively, as well as 2190 bispectral index (BIS) data from 24 Chinese subjects with various renal functions were available. Covariates that may potentially contribute to the PK and PD variability of ciprofol were screened using a stepwise procedure. The optimal ciprofol induction dosing regimen was determined by model-based simulations. The PK of unbound ciprofol could best be described by a three-compartment model, while a two-compartment model could adequately describe unbound M4 PK. The concentrations of total and unbound ciprofol and M4 were linked using a linear protein binding model. The relationship between plasma concentrations of ciprofol and BIS data was best described by an inhibitory sigmoidal Emax model with a two-compartment biophase distribution compartment. Hemoglobin was the identified covariate determining the central compartment clearance of ciprofol; uric acid was a covariate affecting the central compartment clearance of M4 and protein binding rate, kB . The included covariates had no effect on the PD of ciprofol. Simulation results indicated that the label-recommended dose regimen was adequate for anaesthesia induction. The developed model fully characterized the population PK and PD profiles of ciprofol. No dose adjustment is required in patients with mild and moderate renal impairment.

Structure of Self-Initiated Photopolymerized Films: A Comparison of Models.

Self-initiated photografting and photopolymerization (SI-PGP) uses UV illumination to graft polymers to surfaces without additional photoinitiators using the monomers as initiators, "inimers". A wider use of this method is obstructed by a lack of understanding of the resulting, presumably heterogeneous, polymer structure and of the parallel degradation under continuous UV illumination. We have used neutron reflectometry to investigate the structure of hydrated SI-PGP-prepared poly(HEMA-co-PEG10MA) (poly(2-hydroxyethyl methacrylate-co-(ethylene glycol)10 methacrylate)) films and compared parabolic, sigmoidal, and Gaussian models for the polymer volume fraction distributions. Results from fitting these models to the data suggest that either model can be used to approximate the volume fraction profile to similar accuracy. In addition, a second layer of deuterated poly(methacrylic acid) (poly(dMAA)) was grafted over the existing poly(HEMA-co-PEG10MA) layer, and the resulting double-grafted films were also studied by neutron reflectometry to shed light on the UV-polymerization process and the inevitable UV-induced degradation which competes with the grafting.

Model-Based Analysis of a Highly Efficient CO2 Separation Process Using Flexible Metal–Organic Frameworks with Isotherm Hysteresis

To realize large-scale CO2 separation to prevent global warming, energy and space saving separation technologies are required. Flexible metal–organic frameworks (flexible MOFs) with gate-opening properties have been found to be promising adsorbents, but the unconventional sigmoidal shapes and hysteresis of the isotherms have hindered quantitative evaluation of their applications in separation processes. This paper is the first to evaluate ELM-11, a flexible MOF that exhibits sigmoidal isotherms with hysteresis, in a process model and quantify its advantages over a conventional adsorbent. Based on the experimental uptake data, isotherm models for adsorption and desorption were developed, and their parameters were estimated. The resulting isotherm models are incorporated into a rigorous dynamic model of partial differential algebraic equations (PDAEs) to simulate a vacuum pressure swing adsorption (VPSA) process to evaluate the process performance. Numerical challenges to solve the PDAEs, including sigmoidal and hysteresis isotherm models, were resolved with the proposed numerical approaches. Sensitivity analysis for feed pressure and temperature was performed to identify the optimal operating strategy. A comparison with a conventional adsorbent, zeolite 13X, showed that high selectivity and sigmoidal isotherms of ELM-11 give higher productivity and CO2 product purity exceeding 99% without rinse and purge operations as well as lower power consumption for the compressor and vacuum pump.

Sigmoid isostiffness-lines: An in-vitro model for the assessment of aortic stenosis severity.

IntroductionThe aortic valve opening area (AVA), used to quantify aortic stenosis severity, depends on the transvalvular flow rate (Q). The currently accepted clinical echocardiographic method assumes a linear relation between AVA and Q. We studied whether a sigmoid model better describes this relation and determined “isostiffness-lines” across a wide flow spectrum, thus allowing building a nomogram for the non-invasive estimation of valve stiffness.MethodsBoth AVA and instantaneous Q (Qinst) were measured at 10 different mean cardiac outputs of porcine aortic valves mounted in a pulsatile flow loop. The valves' cusps were chemically stiffened to obtain three stiffness grades and the procedure was repeated for each grade. The relative stiffness was defined as the ratio between LV work at grade with the added stiffness and at native stiffness grade. corresponding to the selected of the highest 3 and 5 cardiac output values was predicted in K-fold cross-validation using sequentially a linear and a sigmoid model. The accuracy of each model was assessed with the Akaike information criterion (AIC).ResultsThe sigmoid model predicted more accurately (AIC for prediction of AVA with of the 3 highest cardiac output values: –1,743 vs. –1,048; 5 highest cardiac output values: –1,471 vs. –878) than the linear model.ConclusionThis study suggests that the relation between AVA and Q can be better described by a sigmoid than a linear model. This construction of “isostiffness-lines” may be a useful method for the assessment of aortic stenosis in clinical echocardiography.

Analysis of the Physiological and Yield Performance of Six Quinoa Cultivars in Colombia Under Controlled Conditions

The great diversity of quinoa allows variations in physiological, production, and compositional performance. This study aimed to evaluate six quinoa cultivars through the physiological and nutritional responses of their seeds. Different dynamics were identified in the plant height, and the number of leaves was adjusted to sigmoidal models with R2 greater than 0.97 and 0.77, respectively. The chlorophyll concentration varied through the phenological phases, as did the maximum quantum yield of photosystem II. Differences in the quinoa grains were found between CIEL*a*b* colorimetric coordinates and protein, carbohydrate, and fat contents. In this sense, quinoa cultivars manifest different biological behaviors associated with their genetic nature. Besides, a relationship between cultivars and seed composition was recognized. These results will allow researchers to study other significant differences between the precocity expressed by the Puno, Nariño, and Titicaca cultivars and those with a longer phenological cycle such as the Soracá cultivar.

Growth Rates of Morphometric Variables in Approximately Linear Sections Using Lines in R3

Morphometric analyses have great potential for application in fruit crops, especially in the construction of indices that can be linked to biophysical and/or biochemical quantities of a physiological nature. For example, in peaches, it is convenient to establish quality attributes for harvest or postharvest, where usually the sigmoidal or double sigmoidal models describe the growth of some indicators. The nonlinear nature of this and other associated models sometimes makes it difficult to construct approximate growth rates, so instantaneous rates are used instead. The calculation of approximate rates in nonlinear models may be inappropriate due to aspects related to the phrase known as the “average fallacy.” In this research, different classification algorithms are applied to select the approximately linear phase present in various nonlinear models of variables or parameters used in the modeling of the growth of a crop. A 3D line model was fitted in the extracted section using the decomposition of singular values to generate a simple form of the growth rate. The application was illustrated with growth data of the equatorial and longitudinal diameters of peach fruits measured on different days after defoliation, using data from different elevations above sea level. The proposal simplifies obtaining some growth rates using nonconventional methods; in addition, it allows the comparison and adjustment of the model for the different elevations considered, which provides a novel way for the teaching of certain areas of applied mathematics in plant physiology.

PK/PD integration of florfenicol alone and in combination with doxycycline against Riemerella anatipestifer.

Riemerella anatipestifer (RA) is an important pathogen found in poultry. RA infection can kill ducks and lead to significant economic losses. Seven RA strains with different susceptibility phenotypes were chosen to study the pharmacokinetic/pharmacodynamic (PK/PD) integration of florfenicol (FF) alone and in combination with doxycycline (DOX). The checkerboard assay indicated that synergy [fractional inhibitory concentration index (FICI) ≤ 0.5] was detected in the CVCC3952 strain of RA and that additivity (FICI >0.5 to ≤ 1) was observed in other strains. Static time–kill curves showed that the bactericidal effect of FF against RA was produced at a FF concentration ≥4 MIC, and the antibacterial activity of FF against RA was enhanced from the aspects of efficacy and efficacy in combination with DOX. Dynamic time–kill curves indicated that FF elicited bactericidal activity against the CVCC3857 strain with a reduction ≥4.88 log10CFU/ml when the dose was ≥8 mg/L. However, a bactericidal effect was not achieved at the maximum administered dose of FF monotherapy (20 mg/L) for isolates with a MIC ≥4 μg/ml. The effect of FF against RA was enhanced upon combination with DOX. The combination of FF with DOX reduced the bacterial burden ≥4.53 log10CFU/ml for all strains with a MIC ≥4 μg/ml. Data were fitted to a sigmoidal Emax model. The PK/PD parameters of AUC24h/MIC (the area under the concentration–time curve over 24 h divided by the MIC) and %T >MIC (the cumulative percentage of time over a 24-h period at which the concentration exceeded the MIC) of FF for eliciting a reduction of 3 log10CFU/ml was 40.10 h and 58.71, respectively. For strains with a MIC ≤ 16 μg/ml, the magnitude of the AUC24h/MIC and Cmax/MIC required for a 3 log10CFU/ml of bacterial killing was 34.84 h and 4.74 in the presence of DOX at 0.5 MIC, respectively. These data suggest that combination of FF with DOX enhanced the activity against RA strains with various susceptibilities to FF and DOX.

A Consolidation Curve Reproduction Based on Sigmoid Model: Evaluation and Statistical Assessment.

In the present study, various shapes of laboratory consolidation curves were numerically reproduced using a four-parametric sigmoid function. Sixteen consolidation curves were selected based on one-dimensional oedometer tests to statistically evaluate the sigmoid model and to determine the appropriate deviation statistics. Comparisons between observed and predicted data were performed using the following statistical metrics: mean error (E), root mean square error (RMSE), mean absolute error (MAE), weighted error (WE), revised Nash–Sutcliffe efficiency index (CE1) and refined index of model performance (dr). The weighted error (WE) was chosen as the optimization target in a first-order iterative optimization algorithm to determine a local minimum of a differentiable function. Comparing the simulated and observed settlements showed close correspondence in the values of CE1 and dr in terms of model performance. Based on statistical assessment, the maximum values of RMSE and MAE for the average degree of consolidation were 0.029 (-) and 0.021 (-), respectively. In turn the settlement data RMSE and MAE were 0.039 mm and 0.025 mm, respectively. These results indicated that the sigmoid expression effectively reproduced the shape of the consolidation curve.

Worldwide Lifetime Prediction of c-Si Modules Due to Finger Corrosion: A Phenomenological Approach

Lifetime prediction of solar modules based on laboratory qualification results and location-specific weather data has been a pivotal research problem in the photovoltaic community. Data analytic techniques (e.g., performance loss rate method, statistical clear sky model, Suns-Vmp methods) quantify the integrated degradation from measured data of a solar farm; however, the nonlinear time-dependence of individual degradation and correlation among the degradation modes make it difficult to use the experimentally obtained integrated degradation rates for ultimate lifetime projection. In this article, we use a well-documented, experimentally-validated, and physics-guided empirical (sigmoidal) model to predict c-Si solar module failure caused by temperature and moisture-enhanced contact corrosion. The degradation parameters are obtained from damp-heat qualification tests and the worldwide weather data from NASA/NSRDB databases. Taken together, the model predicts the location-specific power loss and the lifetime of a module exclusively because of contact corrosion. Our results show that a combination of high relative humidity and temperature is needed for higher corrosion; in fact, any decrease in relative humidity increases the lifetime significantly. This model serves as one component of a PV reliability framework that will predict the lifetime of a module that is under various and/or correlated degradation mechanisms including solder bond failure, yellowing, and potential-induced degradations.

Modelling Plant Growth Based on Gompertz, Logistic Curve, Extreme Gradient Boosting and Light Gradient Boosting Models Using High Dimensional Image Derived Maize (<i>Zea mays</i> L.) Phenomic Data

Modelling of plant growth is vital for hypotheses testing and carrying out virtual plant growth and development experiments, which may otherwise take a long time under field conditions. Modelling of plant growth has been aggravated by new phenotyping platforms that generate high dimensional data non-destructively over the entire growth time of a plant using a set of camera system. Such platforms generate high-throughput phenomic data, which is complex and constitute many features collected at multiple growth points for the same plant. However, the classical models are limited in that they can only model a single feature at a time. The objective of this study was to apply dynamic plant growth models that could be used to dissect complex relationships between plant growth and development using several modelling strategies. These included sigmoid, light GBM and XGBoost models. The image derived phenomic data was obtained from the Leibniz Institute of Plant Genetics and Crop Plant Research Gatersleben, Germany. The models were fitted using R statistical software and compared based on RMSE, R-squared, AIC and BIC performance metrics. The results showed that the XGBoost (RMSE = 2.1641) and Light GBM (RMSE = 2.7776) performed better than the Gompertz (RMSE = 3.8378) and the logistic function (RMSE = 3.8378) models in modelling maize plant growth. The XGBoost model (RMSE = 2.1641) showed better performance than Light GBM model (RMSE = 2.7776) in modelling maize plant growth. The Gompertz model using plant volume had AIC and BIC values for 139738.3 and 139763.4, respectively. The Gompertz model for plant side area had AIC and BIC values for 98436.15 and 98461.31, respectively. The logistic function model for plant volume had AIC and BIC values for 139749.2 and 139774.4, respectively. The logistic function model for plant side area had AIC and BIC values for 98415.95 and 98441.11, respectively. The Gompertz model and logistic function models showed almost the same performance in modelling maize plant growth. The non-parametric models, the XGBoost and light GBM, were found to perform better than the classical models (Gompertz and logistic functions) in modelling maize plant growth. Therefore, the study recommends the use of XGBoost as a generic model to fit high dimensional and complex phenotypic data in modelling plant growth and prediction of plant biomass yield at different growth points.

Efficient infection of non-human primates with purified, cryopreserved Plasmodium knowlesi sporozoites

BackgroundPlasmodium falciparum (Pf) sporozoite (SPZ) vaccines are the only candidate malaria vaccines that induce > 90% vaccine efficacy (VE) against controlled human malaria infection and the only malaria vaccines to have achieved reproducible VE against malaria in adults in Africa. The goal is to increase the impact and reduce the cost of PfSPZ vaccines by optimizing vaccine potency and manufacturing, which will benefit from identification of immunological responses contributing to protection in humans. Currently, there is no authentic animal challenge model for assessing P. falciparum malaria VE. Alternatively, Plasmodium knowlesi (Pk), which infects humans and non-human primates (NHPs) in nature, can be used to experimentally infect rhesus macaques (Macaca mulatta) to assess VE.MethodsSanaria has, therefore, produced purified, vialed, cryopreserved PkSPZ and conducted challenge studies in several naïve NHP cohorts. In the first cohort, groups of three rhesus macaques each received doses of 5 × 102, 2.5 × 103, 1.25 × 104 and 2.5 × 104 PkSPZ administered by direct venous inoculation. The infectivity of 1.5 × 103 PkSPZ cryopreserved with an altered method and of 1.5 × 103 PkSPZ cryopreserved for four years was tested in a second and third cohort of rhesus NHPs. The lastly, three pig-tailed macaques (Macaca nemestrina), a natural P. knowlesi host, were challenged with 2.5 × 103 PkSPZ cryopreserved six years earlier.ResultsIn the first cohort, all 12 animals developed P. knowlesi parasitaemia by thick blood smear, and the time to positivity (prepatent period) followed a non-linear 4-parameter logistic sigmoidal model with a median of 11, 10, 8, and 7 days, respectively (r2 = 1). PkSPZ cryopreserved using a modified rapid-scalable method infected rhesus with a pre-patent period of 10 days, as did PkSPZ cryopreserved four years prior to infection, similar to the control group. Cryopreserved PkSPZ infected pig-tailed macaques with median time to positivity by thin smear, of 11 days.ConclusionThis study establishes the capacity to consistently infect NHPs with purified, vialed, cryopreserved PkSPZ, providing a foundation for future studies to probe protective immunological mechanisms elicited by PfSPZ vaccines that cannot be established in humans.

Recommendations for nasotracheal tube insertion depths in neonates.

BackgroundEndotracheal tube (ETT) malposition is common in neonatal intubation. Recommendations for ETT insertion depths predominantly address orotracheal intubation. The aim of this study was to develop gestational age-, weight-, and length-based curve charts and tables for nasotracheal ETT insertion depth recommendations in neonates.MethodIn this retrospective single-center study, the individual optimal ETT insertion depths in neonates were determined by evaluating postintubation radiographic images. Gestational age-, weight-, and length-based best-fit curves and tables were generated using regression analysis to calculate related ETT insertion depths. The insertion depths predicted by the models were compared with previously published recommendations.ResultsWe analyzed intubations of 178 neonates (gestational age range at intubation: 23.7–43.0 weeks). Applying sigmoidal logistic regression models, curves, and tables revealed R2 values between 0.766 and 0.837. The insertion depths predicted by the models revealed certain deviations when compared with four previously published recommendations for nasotracheal ETT depth estimation in neonates.ConclusionThe charts and tables developed in this study enable a fast and accurate determination of recommended nasotracheal ETT insertion depths in neonates.

SOLUBLE GUANYLYL CYCLASE ACTIVATION RESCUES HYPEROXIA-INDUCED DYSFUNCTION OF VASCULAR RELAXATION.

Introduction: Perioperative alterations in perfusion lead to ischemia and reperfusion injury, and supplemental oxygen is administered during surgery to limit hypoxic injury but can lead to hyperoxia. We hypothesized that hyperoxia impairs endothelium-dependent and endothelium-independent vasodilation but not the vasodilatory response to heme-independent soluble guanylyl cyclase activation. Methods: We measured the effect of oxygen on vascular reactivity in mouse aortas. Mice were ventilated with 21% (normoxia), 60% (moderate hyperoxia), or 100% (severe hyperoxia) oxygen during 30 minutes of renal ischemia and 30 minutes of reperfusion. After sacrifice, the thoracic aorta was isolated, and segments mounted on a wire myograph. We measured endothelium-dependent and endothelium-independent vasodilation with escalating concentrations of acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, and we measured the response to heme-independent soluble guanylyl cyclase activation with cinaciguat. Vasodilator responses to each agonist were quantified as the maximal theoretical response ( Emax ) and the effective concentration to elicit 50% relaxation (EC 50 ) using a sigmoid model and nonlinear mixed-effects regression. Aortic superoxide was measured with dihydroethidium probe and high-performance liquid chromatography quantification of the specific superoxide product 2-hydroxyethidium. Results: Hyperoxia impaired endothelium-dependent (ACh) and endothelium-independent (SNP) vasodilation compared with normoxia and had no effect on cinaciguat-induced vasodilation. The median ACh Emax was 76.4% (95% confidence interval = 69.6 to 83.3) in the normoxia group, 53.5% (46.7 to 60.3) in the moderate hyperoxia group, and 53.1% (46.3 to 60.0) in the severe hyperoxia group ( P < 0.001, effect across groups), while the ACh EC 50 was not different among groups. The SNP Emax was 133.1% (122.9 to 143.3) in normoxia, 128.3% (118.1 to 138.6) in moderate hyperoxia, and 114.8% (104.6 to 125.0) in severe hyperoxia ( P < 0.001, effect across groups), and the SNP EC 50 was 0.38 log M greater in moderate hyperoxia than in normoxia (95% confidence interval = 0.18 to 0.58, P < 0.001). Cinaciguat Emax and EC 50 were not different among oxygen treatment groups (median range Emax = 78.0% to 79.4% and EC 50 = -18.0 to -18.2 log M across oxygen groups). Aorta 2-hydroxyethidium was 1419 pmol/mg of protein (25th-75th percentile = 1178-1513) in normoxia, 1993 (1831-2473) in moderate hyperoxia, and 2078 (1936-2922) in severe hyperoxia ( P = 0.008, effect across groups). Conclusions: Hyperoxia, compared with normoxia, impaired endothelium-dependent and endothelium-independent vasodilation but not the response to heme-independent soluble guanylyl cyclase activation, and hyperoxia increased vascular superoxide production. Results from this study could have important implications for patients receiving high concentrations of oxygen and at risk for ischemia reperfusion-mediated organ injury.

Data-driven Models for Wind Speed Forecasting in Malacca State

Wind energy is a type of renewable energy that has received much attention in the electricity market. This study focuses on forecasting wind speed at Malacca state’s Station. This paper proposes using a Group Method of Data Handling (GMDH) model with a hyperbolic tangent transfer function in forecasting wind speed data in Malacca state. The performance of this model is compared with three other models: Artificial neural network (ANN) hyperbolic tangent, ANN log sigmoid and GMDH model. In addition, this study investigates the impact of using different transfer functions in data-driven models for forecasting wind speed. Usually, the application of the GMDH model only implements the second-order polynomial as a partial description. However, in this study, we implement the hyperbolic tangent transfer function in the GMDH model. The forecasting model’s accuracy is evaluated using mean absolute percentage error (MAPE), root mean square error (RMSE) and mean absolute error (MAE). The results show that the GMDH model with hyperbolic tangent is highly accurate with more negligible computational power than other models. The GMDH-hyperbolic tangent model managed to improve the forecasting performance of the conventional GMDH model by 11.21% in mean absolute percentage error and outperforms other ANN models.

Valorization of dairy by-products: Optimized synthesis of 5-hydroxymethylfurfural and levulinic acid from lactose and whey

Whey is a by-product of the dairy industry that has a high proportion of organic material. To valorize whey, the optimization of the synthesis of 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) from lactose and whey by utilizing a Brönsted acid as a catalyst was performed. The Box-Behnken statistical model was used to analyze and optimize reciprocal interactions between the reaction variables. As a result, 45.6% yield of LA from 0.3 M lactose and 0.6 M HCl catalyst/M substrate was achieved at a reaction temperature of 195 °C for 60 min. In addition, 25.4% yield of 5-HMF was obtained from 0.2 M whey (as lactose) and 0.3 M HCl/M substrate by heating it to 195 °C for 45 min. More 5-HMF was obtained from whey than lactose under identical reaction conditions. While lactose was converted more rapidly than whey to LA. A nonlinear sigmoid model producing high coefficient of determination values adequately explained the effects of combined severity factor levels on 5-HMF and LA yields from lactose. On the other hand, the case of whey was not well-matched with low R2 values. These findings imply that the use of lactose and whey as feedstocks for platform chemical synthesis will continue.

Recovery of biomethane from a submerged anaerobic membrane bioreactor treating domestic wastewater blended with semi-solid organic wastes discharged from residential establishments

Recent research studies on the innovative concept of submerged anaerobic membrane bioreactor (SAnMBR) technology have demonstrated superior treatment and operational performance for treating a broad range of waste streams discharged from various industries. This study aimed to investigate the treatment and recovery of biomethane (bio-CH4) performance of ceramic ultrafiltration (UF) coupled with ”co-digestion based SAnMBR”, which was not previously studied by others, for treating an organic fraction of food waste (OFFW) blended with domestic wastewater (DWW) at surge organic loading rates (OLRs) disposed at modern high-rise establishments and similar residential clusters. The SAnMBR was operated in five phases (Phase 1–5), with different organic loading rates (OLRs) varying from 0.49 to 22.57 kg-COD/m3/d. All bio-CH4, mixed liquor sludge, and treated permeate samples were analyzed using standard methods. The key parameters representing the cumulative bio-CH4 yield during each phase were estimated using sigmoidal models, and the simulated results were validated using ANOVA. It was found that the SAnMBR produced high-quality, low-turbid reclaimed water showing an increasing trend in yield of bio-CH4 with an increase of OLR. It was also observed that the SAnMBR demonstrated stable and superior treatment performance at shock-loads of organics. The maximum bio-CH4 yield recorded during the study was 73.06 ± 6.48%. The findings of this study confirmed the suitability of applying this novel concept of ”co-digestion-based SAnMBR” towards sustainable and efficient waste management in modern-high rise establishments.

Design and Fabrication of Substrate-Free Au/SiNx/Au Metafilm for THz Sensing Application

A method of designing and fabricating substrate-free Au/SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> /Au metafilms as the terahertz (THz) absorber of metamaterial focal plane arrays (MFPA) is reported. The absorption was investigated by the finite integration method simulation and new explicit functions. The substrate-free structure was well fabricated by microelectromechanical system (MEMS) technology. The frequency-dependent absorption of MFPA was measured by THz time-domain spectroscopy (THz-TDS) system. It exhibits an extremely high absorptance of 98.7% at 1.36 THz. The absorption characteristic shows an asymmetric profile, which is well fitted with an Asymmetric Double Sigmoidal (Asym2sig) model. Our results show that the Au/SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> /Au metafilms have potential in optical readout THz real-time imaging, and highly sensitive sensing applications.

Proposing a novel double sigmoidal model to fit the master curve for various polymer-modified asphalt

ABSTRACT Master curve technique is frequently used to characterize the linear viscoelasticity of polymer modified asphalt (PMA), however, there is no widely accepted master curve for PMA. This study aims to propose a novel double sigmoidal model that can be used universally for all asphalts, especially highly modified PMAs. To do so, one plain asphalt and six representative PMAs are examined. Extended temperature sweep tests (−40°C to 140°C) are conducted to grasp the whole picture of the master curve. Three representative mathematical models (CAM, sigmoidal, double sigmoidal) are selected and compared in terms of fitting in both modulus and phase angle. The results suggest that double sigmoidal model suits all types of asphalts for all testing temperature ranges, and it features the ability to model the rubbery state and rubbery-viscous transition of highly modified PMA (RMSE < 0.02). A phase angle expression of the double sigmoidal model is also developed, which shows great potential in characterizing the strength of polymer network within the PMA. Also, it avoids the impact from the partial break of the time-temperature superposition principle (TTSP) and reveals the true shape of the phase angle master curve. Finally, master curve models are recommended based on different testing temperature ranges.