Linear Polynomial Models Research Articles

Component distribution associated with phase separation and purification of tropical almond biodiesel at different temperatures

Accurate knowledge of the components in the purification of biodiesel is important in achieving consistency in quality for the separation and purification process. In this paper, ternary phase diagrams were used to study the phase separation and purification of tropical almond biodiesel at temperatures of 20 °C, 30 °C and 40 °C. The biodiesel was produced using alkaline transesterification of the seed oil. The biodiesel was characterized using ASTM and EN standard methods. A modified cloud point titration procedure under constant temperature was used to determine the tie lines and binodal compositions. The phase mixture compositions were determined using gas chromatographic method. Distribution coefficient and selectivity analysis were performed and data accuracy, consistency and reliability were done using a first-order linear polynomial model. The result revealed free fatty acid values for the oil and the biodiesel as 0.63 and 0.23 respectively. The data quality and reliability showed a high coefficient of determination of 0.9998, adjusted coefficient of determination of 0.9887, a standard deviation of 0.0327, and a correlation coefficient of 0.8349 at the investigated temperatures. Methanol was prevalent in the glycerol phase. Ternary phase diagrams provided the visual means of estimating the distribution of the components.

Use of different proportions of rice milling fractions as strategy for improving quality parameters and nutritional profile of gluten-free bread.

The growing consumer exigency and the lack of gluten-free (GF) bakery products with good technological and nutritional characteristics in the market have increase the need of researching in this area. Few studies have analysed the simultaneous influence of different flour fractions from rice dry milling to formulate GF bread and its effects on rheology and product quality. The aim of this study was to characterize the chemical and physical properties of rice milling fractions (flour, coarse, bran); and to evaluate the effect of these fractions on rheology, and quality of GF bread. High fibre content (31.5%) and good hydration and functional properties demonstrated the suitability of bran for food development. A mixture design with three components was used. Pasting parameters, bread specific volume (BSV), firmness and colour intensity (Chr) responses were fitted to linear and quadratic polynomial models. The presence of bran in the blends reduced almost all pasting parameters. The optimal mixture proportion was flour:coarse:bran (45:35:20), presenting a BSV 1.7 ± 0.1 cm3/g; firmness 0.23 ± 0.01MPa, and Chr 23.8 ± 0.4. A portion (50g) of GF bread increased four times the dietary fibre intake. The utilization of different rice fractions to formulate GF bread improved the product quality and enhance the nutritional profile.

Small airway loss in the physiologically ageing lung: a cross-sectional study in unused donor lungs

Physiological lung ageing is associated with a gradual decline in dynamic lung volumes and a progressive increase in residual volume due to diminished elastic recoil of the lung, loss of alveolar tissue, and lower chest wall compliance. However, the effects of ageing on the small airways (ie, airways <2·0 mm in diameter) remain largely unknown. By using a combination of ex-vivo conventional CT (resolution 1 mm), whole lung micro-CT (resolution 150 μm), and micro-CT of extracted cores (resolution 10 μm), we aimed to provide a multiresolution assessment of the small airways in lung ageing in a large cohort of never smokers. For this cross-sectional study, we included donor lungs collected from 32 deceased never-smoking donors (age range 16-83 years). Ex-vivo CT and whole lung high-resolution CT (micro-CT) were used to determine total airway numbers, stratified by airway diameter. Micro-CT was used to assess the number, length, and diameter of terminal bronchioles (ie, the last generation of conducting airways); mean linear intercept; and surface density in four lung tissue cores from each lung, extracted using a uniform sampling approach. Regression β coefficients are calculated using linear regression and polynomial models. Ex-vivo CT analysis showed an age-dependent decrease in the number of airways of diameter 2·0 mm to less than 2·5 mm (β coefficient per decade -0·119, 95% CI -0·193 to -0·045; R2=0·29) and especially in airways smaller than 2·0 mm in diameter (-0·158, -0·233 to -0·084; R2=0·47), between 30 and 80 years of age, but not of the larger (≥2·5 mm) diameter airways (-0·00781, -0·04409 to 0·02848; R2=0·0007). In micro-CT analysis of small airways, the total number of terminal bronchioles per lung increased until the age of 30 years, after which an almost linear decline in the number of terminal bronchioles was observed (β coefficient per decade -2035, 95% CI -2818 to -1252; R2=0·55), accompanied by a non-significant increase in alveolar airspace size (6·44, -0·57 to 13·45, R2=0·10). Moreover, this decrease in terminal bronchioles was associated with the age-related decline of pulmonary function predicted by healthy reference values. Loss of terminal bronchioles is an important structural component of age-related decline in pulmonary function of healthy, non-smoking individuals. Research Foundation-Flanders, KU Leuven, Parker B Francis Foundation, UGent, Canadian Institutes for Health.

Assessment of Lead (Pb) in Soil at Various Distances and Depths at Pb and Zn Mining Site in Ishiagu, Ebonyi State, Nigeria

Pb in soil at various distance and depths was assessed at Pb and Zn mining site in Ishiagu Ebonyi State, Nigeria to determine the furthest distance travelled so far and the concentration at the distance. Pb ion in sampled soils at depth 0-10, 10-20, 20-30, 30-40 and 40-50 cm within pollution zones in 1 km x 1 km area of 100 m grid intervals were fitted with mathematical models for prediction using MATLAB. Pb ion change with distance was fitted into power model and linear polynomial models at distinct grid points. The models predictions showed decrease in Pb ion with distance. It revealed that the ion had travelled far into the soil with a furthest distance of 4760 cm but with no soil pollution signal because 64.54 mg/kg (concentration at 4760 cm) is less than 100 mg/kg specified as the maximum for soils. It showed a signal that the metal might threaten the ground water at some future date with an objectionable concentration above 0.01 mg/l specified for drinking water. Concentration at some intermediate distances is risk signal of food pollution through absorption of the metal by crops with root morphology and depth reaching these intermediate depths of objectionable concentration.

Temperature variations evidenced by records on the latest spring snowing dates in Hangzhou of eastern China during 1131-1270AD

We collected and verified documentary records of the latest spring snowing dates (LSSD) in Hangzhou during Southern Song Dynasty. Furtherly, the statistical correlation between this proxy and February–April mean temperature in Hangzhou was examined, and samples later than the perennial mean of the LSSD during Southern Song Dynasty were transformed into the decadal mean of LSSD by means of Boltzmann function. General characteristics of this reconstructed LSSD series with a 10-year temporal resolution was analyzed, and it was also compared with other documentary evidences and reconstructed climate series in China for the period 1131–1270. The results and discussion suggested that: (1) Records of the LSSD in Hangzhou during Southern Song Dynasty did not refer to ice pellets and graupels, which had an explicit climate significance (−0.34°C/10d, R2=0.37, p<0.001). However, when this proxy is used to reconstruct temperature changes, all dates should be converted into proleptic Gregorian style and meet the same criterion of “true Qi” as the Chinese traditional calendar after 1929. (2) The decadal mean of LSSD can be effectively estimated by using the forefront of LSSD in the decade on the basis of Boltzmann function, whose extrapolation has a lesser uncertainty than those on the basis of linear models or polynomial models. (3) The spring climate in Hangzhou during 1131–1270 was almost as warm as the period 1951–1980. At the centennial scale, this period can be divided into two phases: the cold 1131–1170 and the warm 1171–1270. In the latter, 1181–1200 and 1221–1240 were two cold intervals at the multi-decadal scale. (4) The reconstructed LSSD series was consistent well with other documentary evidences and reconstructed climate series in China for 1131–1270, which may reflect the influence on the climate over most regions of China imposed by the Pacific Decadal Oscillation (PDO).

Temporal and Spatial Variations of Chlorophyll a Concentration and Eutrophication Assessment (1987–2018) of Donghu Lake in Wuhan Using Landsat Images

Chlorophyll a (Chl-a) concentration, which reflects the biomass and primary productivity of phytoplankton in water, is an important water quality parameter to assess the eutrophication status of water. The band combinations shown in the images of Donghu Lake (Wuhan City, China) captured by Landsat satellites from 1987 to 2018 were analyzed. The (B4 − B3)/(B4 + B3) [(Green − Red)/(Green + Red)] band combination was employed to construct linear, power, exponential, logarithmic and cubic polynomial models based on Chl-a values in Donghu Lake in April 2016. The correlation coefficient (R2), the relative error (RE) and the root mean square error (RMSE) of the cubic model were 0.859, 9.175% and 11.194 μg/L, respectively and those of the validation model were 0.831, 6.509% and 19.846μg/L, respectively. Remote sensing images from 1987 to 2018 were applied to the model and the spatial distribution of Chl-a concentrations in spring and autumn of these years was obtained. At the same time, the eutrophication status of Donghu Lake was monitored and evaluated based on the comprehensive trophic level index (TLI). The results showed that the TLI (∑) of Donghu Lake in April 2016 was 63.49 and the historical data on Chl-a concentration showed that Donghu Lake had been eutrophic. The distribution of Chl-a concentration in Donghu Lake was affected by factors such as construction of bridges and dams, commercial activities and enclosure culture in the lake. The overall distribution of Chl-a concentration in each sub-lake was higher than that in the main lake region and Chl-a concentration was highest in summer, followed by spring, autumn and winter. Based on the data of three long-term (2005–2018) monitoring points in Donghu Lake, the matching patterns between meteorological data and Chl-a concentration were analyzed. It revealed that the Chl-a concentration was relatively high in warmer years or rainy years. The long-term measured data also verified the accuracy of the cubic model for Chl-a concentration. The R2, RE and RMSE of the validation model were 0.641, 2.518% and 22.606 μg/L, respectively, which indicated that it was feasible to use Landsat images to retrieve long-term Chl-a concentrations. Based on longitudinal remote sensing data from 1987 to 2018, long-term and large-scale dynamic monitoring of Chl-a concentrations in Donghu Lake was carried out in this study, providing reference and guidance for lake water quality management in the future.

Annual variation characteristics of eutrophication in Dongting Lake, China

The seasonal variation characteristics of eutrophication based on HJ-1 data and synchronous observation data on the ground were studied to provide a theoretical basis for the restoration and management of eutrophication in Dongting Lake. The remote sensing model of chlorophyll-a concentration inversion was established through the comparative analysis of the linear model, exponential model, logarithmic model and quadratic polynomial model by 38 kinds of band combinations. The average relative error was 22.81%. The RMSE of 13.71 mg/m3was far lower than the average concentration of 34.16 mg/m3. The results showed the following. (i) From the perspective of time distribution, the eutrophication degree decreased successively in summer, autumn, spring, and winter. Dongting Lake is mainly in the state of moderate nutrition, which may be attributed to its unique hydrological conditions (short water cycle and fast flow rate). (ii) Eutrophicated water bodies are mainly distributed in the East Dongting Lake and inner lake where the water flow is relatively slow. The water bodies with pool nutrient status are mainly distributed in the outer lake areas where the water flows faster, such as West Dongting Lake.

Atypical age-related changes in cortical thickness in autism spectrum disorder

Recent longitudinal neuroimaging and neurophysiological studies have shown that tracking relative age-related changes in neural signals, rather than a static snapshot of a neural measure, could offer higher sensitivity for discriminating typically developing (TD) individuals from those with autism spectrum disorder (ASD). It is not clear, however, which aspects of age-related changes (trajectories) would be optimal for identifying atypical brain development in ASD. Using a large cross-sectional data set (Autism Brain Imaging Data Exchange [ABIDE] repository; releases I and II), we aimed to explore age-related changes in cortical thickness (CT) in TD and ASD populations (age range 6–30 years old). Cortical thickness was estimated from T1-weighted MRI images at three scales of spatial coarseness (three parcellations with different numbers of regions of interest). For each parcellation, three polynomial models of age-related changes in CT were tested. Specifically, to characterize alterations in CT trajectories, we compared the linear slope, curvature, and aberrancy of CT trajectories across experimental groups, which was estimated using linear, quadratic, and cubic polynomial models, respectively. Also, we explored associations between age-related changes with ASD symptomatology quantified as the Autism Diagnostic Observation Schedule (ADOS) scores. While no overall group differences in cortical thickness were observed across the entire age range, ASD and TD populations were different in terms of age-related changes, which were located primarily in frontal and tempo-parietal areas. These atypical age-related changes were also associated with ADOS scores in the ASD group and used to predict ASD from TD development. These results indicate that the curvature is the most reliable feature for localizing brain areas developmentally atypical in ASD with a more pronounced effect with symptomatology and is the most sensitive in predicting ASD development.

The study of parametric optimization algorithms on example of vehicle bumper crashworthiness

Different algorithms of parametric optimization (implemented in the program LS-OPT) to solve high-speed and high-nonlinear problems of impact character on the example of vehicle bumper optimization are considered and compared. Different algorithms of response surface optimization such as linear polynomial model, quadratic polynomial model, Feedforward, Radial Basis Function, Kriging and Support Vector Regression were studied and analyzed; algorithms of choosing point selection scheme were considered. The analysis of optimization results allowed us to determine which of these algorithms are most effective in terms of accuracy and computational time. The problem of impact on the vehicle’s bumper is solved in the paper, the optimization is based on the application of metamodel (RBF). The method provided a reduction of its mass by 16% while maintaining the initial parameters of crashworthiness.

Regression Analysis in Political Science Research Using the R Program

The aim of the article is to present the basic functionalities of the R program for the creation of regression models describing political phenomena. A database of voter turnout during the 2014 U.S. Congress elections categorised according to voters’ age was used for the analyses. The statistical procedures (linear and second-degree polynomial models) applied were discussed in detail, with paths to their respective commands being provided. The article is addressed primarily to postgraduate students in political science and related disciplines, as well as to researchers who have never used the R program before.

Comparison of different mathematical models to assess seasonal variations in the longevity of DNA integrity of cooled‐stored stallion sperm

Dynamic assessment of sperm DNA fragmentation (SDF) has shown to give fuller understanding of stallion semen quality; however, there have been limited attempts to use this parameter to investigate seasonal changes in productive functions. The aims of this study were to: (a) establish a reliable mathematical model to describe the longevity of cooled-stored sperm DNA integrity; (b) to examine the effect of seasonal variations on SDF. Ejaculates were cooled to 5°C, and SDF was analysed after 0, 6 and 24hr of storage. The coefficient of determination (R2 ) was calculated after fine-tuning linear (LIN), exponential (EXP) and second order polynomial (POL) models. R2 was significantly higher (p<.001) for POL than for LIN and EXP. The rate of DNA degradation was calculated using the slopes of POL equations. After assessing the rate of change of the POL functions, significant differences between the acceleration of DNA fragmentation were found (p<.01) among seasons, being higher for winter and summer than spring and autumn. In conclusion, DNA analysis of stallion sperm fits better to a second order polynomial mathematical model, being spring the best season to collect and process cooled stallion semen in order to maintain the DNA integrity of the stallion sperm.

Comparison of polynomial and nonlinear models on description of pepper growth

Pepper (Capsicum sp.) is important for the Brazilian agribusiness, serving as raw material for the food, pharmaceutical and cosmetic industries. The adequate evaluation of its plants growth may help in understanding the causes of crops yield variation, with it being able to be studied by regression models, which help to adequate the management with the different phenological phases. This study aimed to compare the fit of linear Polynomial model and the Logistic and Gompertz nonlinear models in the description of pepper plants growth from the Doce cultivar. Estimates were obtained by the Gauss-Newton method, with the quality of fitted models compared by graphical analysis and evaluators: adjusted coefficient of determination (R2 adj), Residual Standard Deviation (RSD) and the corrected Akaike Information Criterion (AICc). Residues were normal, independent and homocedastic at 5% level of significance. All models properly described the height of the Doce cultivar. The Logistic model was the most adequate according to the fitting evaluators, having higher value of R2 adj, and lower RSD and AICc values.

Study of the Compression Behavior of Steel-Fiber Reinforced Concrete by Means of the Response Surface Methodology

The compression behavior of steel-fiber reinforced concrete (SFRC) has been addressed exhaustively in recent decades thereby highlighting a variety of differences with regard to the effect that the addition of fiber has on it. In this paper, a detailed study of the subject is developed for which a database has been created, which includes 197 tests performed on cylindrical concrete specimens with dimensions of 150 × 300 mm 2 (diameter × height). By means of the response surface methodology, we disclose the relationship that exists between the geometric parameters of the fiber (length, diameter, and aspect ratio), their amount (fraction in volume), and some matrix parameters (compression resistance and maximum size of coarse aggregate) with the different compression responses of the SFRC, which are strength, elastic modulus, critical deformation under maximum load, and the volumetric deformation work in the pre- and post-peak branch. Linear polynomial models are chosen to adjust each response with the defined factors, and said variables are studied in a dimensional and non-dimensional format. From the results obtained, it is verified how the inclusion of steel-fibers produces notable improvements in ductility and the energy absorption capacity of the concrete when significantly increasing the works of volumetric deformation in the pre- and post-peak branch with respect to the matrix without fibers. In addition, a new model is analyzed, which describes the stress–strain curve of the compression behavior of the SFRC based on the increase of ductility and energy absorption. This model is characterized by a softening branch subsequent to the peak load determined by means of the residual compressive strength, a parameter that corresponds to the value of the compressive stress associated with a strain equal to three times that of the peak of the curve, which is significantly dependent on the aspect ratio and fiber content.

Highly accurate prediction of flammability limits of chemical compounds using novel integrated hybrid models.

Two novel and highly accurate hybrid models were developed for the prediction of the flammability limits (lower flammability limit (LFL) and upper flammability limit (UFL)) of pure compounds using a quantitative structure–property relationship approach. The two models were developed using a dataset obtained from the DIPPR Project 801 database, which comprises 1057 and 515 literature data for the LFL and UFL, respectively. Multiple linear regression (MLR), logarithmic, and polynomial models were used to develop the models according to an algorithm and code written using the MATLAB software. The results indicated that the proposed models were capable of predicting LFL and UFL values with accuracies that were among the best (i.e. most optimised) reported in the literature (LFL: R2 = 99.72%, with an average absolute relative deviation (AARD) of 0.8%; UFL: R2 = 99.64%, with an AARD of 1.41%). These hybrid models are unique in that they were developed using a modified mathematical technique combined three conventional methods. These models afford good practicability and can be used as cost-effective alternatives to experimental measurements of LFL and UFL values for a wide range of pure compounds.

Исследование эффективности алгоритмов параметрической оптимизации применительно к процессам ударного воздействия на примере бампера и кабины автомобиля

This article compares various parametric optimization algorithms implemented in LS-OPT for solving high-speed and highly nonlinear impact problems using a bumper beam and a truck cabin as examples. The analysis of the results showed which algorithms were the most effective according to the criteria of accuracy and time. The metamodel based on the RBF neuron network and the space-filling point selection for optimizing the design of the bumper beam allowed reducing the mass of the structure by 16 % while maintaining the same parameters of rigidity and power consumption. To solve optimization problems concerning passive safety of complex structures such as truck cabins, the RBF neuron network model proved to be the most effective. It is therefore recommended as the primary model, while the linear polynomial model should be used only for preliminary analysis.

The estimation of mango fruit total soluble solids using image processing technique

Appearance and color, as the most important factors selected by consumers for the agricultural products, are related to the chemical and sensory properties. The present study aimed to evaluate the efficiency of image processing as a simple, rapid and non-destructive alternate for estimating mango quality indices. Thus, mango fruits were kept under different temperature conditions, and accordingly the fruits were evaluated several times by using image processing. The results indicated that the value of a* reached from −12.4 to −2.5 at 24 °C, while it increased from −10.09 to −2.43 at 15°C. The b* values of fruits in ambient temperature was higher than those in chilling conditions. Furthermore, differences among L* value of three storage conditions was found during seven-step evaluation periods. The fruits kept at cold conditions could display the internal browning area after the second and third observation period at 5°C and 15°C, respectively. Based on the results, the linear regression (R2 = 0.83) and polynomial (R2 = 0.84) models between Normalized a* and TSS is related to keeping fruit at 24 °C, while an obvious polynomial relationship was observed at 15°C (R2 = 0.78) and 5°C (R2 = 0.98).

Dynamic Range of the Peripapillary Retinal Vessel Density for Detecting Glaucomatous Visual Field Damage

To evaluate the dynamic range of peripapillary retinal vessel density (ppVD) for predicting the severity of visual field (VF) damage in comparison with that of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) in primary open-angle glaucoma (POAG) patients and to determine the severity of VF damage below which progressive VF loss becomes undetectable based on either ppVD or cpRNFLT. Cross-sectional study. One hundred thirty-three POAG patients having ppVD, cpRNFLT, and VF sensitivity (VFS) measurements evaluated using OCT angiography, spectral-domain OCT, and standard automated perimetry, respectively. Correlations between ppVD and VFS (vessel-function) and between cpRNFLT and VFS (structure-function) were assessed using both linear and fractional polynomial (FP) models. Davies' test was used to determine the breakpoints for VFS below which progressive VF loss became undetectable based on ppVD or cpRNFLT. Comparison of the vessel-function and structure-function correlations, and the VFS breakpoints in each correlation. Both ppVD and cpRNFLT exhibited significant linear correlations with VFS globally. In the temporal-superior, temporal, and temporal-inferior sectors, the correlations were explained better by the FP model than by the linear model for both ppVD (P ≤ 0.009) and cpRNFLT (P ≤ 0.008). The breakpoints for VFS in the vessel-function and structure-function correlations were -8.28 dB and -6.41 dB, respectively, in the temporal-superior sector, -11.83 dB and -8.42 dB, respectively, in the temporal sector, and -7.92 dB and -6.28 dB, respectively, in the temporal-inferior sector. The sectoral ppVD exhibits curvilinear correlations with VFS and has significant breakpoints below which the VFS decline becomes undetectable. The VFS breakpoints were lower for ppVD than for cpRNFLT, indicating that the dynamic range of ppVD is potentially larger for detecting more advanced VF damage.

Influence of Frailty on Cognitive Decline: A Population-Based Cohort Study in Rural Ecuador

ObjectiveTo assess the influence of frailty on cognitive decline. DesignPopulation-based prospective cohort study. Settings/participantsCommunity-dwelling older adults living in a rural Ecuadorian village, fulfilling the following criteria: age ≥60 years at baseline Montreal Cognitive Assessment (MoCA) and frailty assessment, a baseline brain magnetic resonance imaging, and a follow-up MoCA performed at least 12 months after the baseline. MeasuresFrailty was evaluated by the Edmonton Frailty Scale (EFS) and cognitive performance by MoCA. The relationship between baseline EFS and MoCA decline was assessed by longitudinal linear and fractional polynomial models, adjusted for relevant confounders. The score of the cognitive component of the EFS was subtracted, and an alternative fractional polynomial model was fitted to settle the impact of such cognitive question on the model. ResultsA total of 252 individuals, contributing 923.7 person-years of follow-up (mean: 3.7 ± 0.7 years) were included. The mean EFS score was 4.7 ± 2.5 points. The mean baseline MoCA score was 19.5 ± 4.5 points, and that of the follow-up MoCA was 18.1 ± 4.9 points (P = .001). Overall, 154 (61%) individuals had lower MoCA scores in the follow-up. The best fitted longitudinal linear model showed association between baseline EFS score and MoCA decline (P = .027). There was a continuous increase in MoCA decline in persons with an EFS ≥7 points (nonlinear relationship). Fractional polynomials explained the effect of the EFS on MoCA decline. For the complete EFS score, the β coefficient was 2.43 (95% confidence interval 1.22–3.63). For the effect of the EFS (without its cognitive component) on MoCA decline, the relationship was still significant (β 4.86; 95% confidence interval 2.6–7.13). Conclusions/implicationsOver a 3.7-year period, 61% of older adults living in Atahualpa experienced cognitive decline. Such decline was significantly associated with frailty status at baseline. Region-specific risk factors influencing this relationship should be further studied to reduce its burden in rural settings.

Non-linear curve adjustments widen biological interpretation of relative growth analyses of the clam Tivela mactroides (Bivalvia, Veneridae).

Evaluation of relative (allometric) growth provides useful information to understand the development of organisms, as well as to aid in the management of fishery-exploited species. Usually, relative growth analyses use classical models such as the linear equation or the power function (allometric equation). However, these methods do not consider discontinuities in growth and may mask important biological information. As an alternative to overcome poor results and misleading interpretations, recent studies have suggested the use of more complex models, such as non-linear regressions, in conjunction with a model selection approach. Here, we tested differences in the performance of diverse models (simple linear regression, power function, and polynomial models) to assess the relative growth of the trigonal clam Tivela mactroides, an important fishing resource along the South American coast. Regressions were employed to relate parameters of the shell (length (L), width (W), height (H) and weight (SW)) among each other and with soft parts of the organism (dry weight (DW) and ash-free dry weight (ASDW)). Then, model selection was performed using the information theory and multi-model inference approach. The power function was more suitable to describe the relationships involving shell parameters and soft parts weight parameters (i.e., L vs. SW, DW, and AFDW, and SW vs. DW). However, it failed in unveiling changes in the morphometric relationships between shell parameters (i.e., L vs. W and H; W vs. H) over time, which were better described by polynomial functions. Linear models, in turn, were not selected for any relationship. Overall, our results show that more complex models (in this study polynomial functions) can unveil changes in growth related to modifications in environmental features or physiology. Therefore, we suggest that classical and more complex models should be combined in future studies of allometric growth of molluscs.

Effect of High-pressure Densification on Moisture Sorption Properties of Paulownia Wood

The effect of high-pressure (HP) densification (30, 90, and 150 MPa for 3, 30, and 300 s) on the moisture sorption properties of Paulownia wood was investigated. After the densification, samples were conditioned at three temperatures (20, 30, and 40 °C) and five equilibrium moisture contents (from 11.20 to 95.62%) during the study, after which the equilibrium moisture contents of the control and treated samples were measured. The HP-treated groups had higher equilibrium moisture contents than the controls at higher relative humidity levels. The hysteresis phenomenon and the scanning electron microscopy observations were explained by the transformation of the structural elements by the HP treatment. Finally, two moisture sorption isotherm (MSI) models (a linear polynomial model for adsorption and a quadratic polynomial model for desorption) were established with good performance to describe the relationship between HP treatment parameters, environmental conditions, and equilibrium moisture contents.