Amino acid profiling and antimicrobial activity of Cucurbita moschata and Lagenaria siceraria seed protein hydrolysates

Cucurbita moschata and Lagenaria siceraria seed proteins were extracted and hydrolysed with trypsin in order to recover antibacterial peptides. Amino acid content and molecular weight distribution were estimated to justify their co-relationship with antimicrobial activity. Antimicrobial activities of C. moschata and L. siceraria seed protein hydrolysates against three Gram-negative bacteria and two Gram-positive bacteria were evaluated. Seed protein hydrolysates of both of these plants have significantly higher activity against Acinetobacter baumannii (p < 0.05). The lethal concentration (LC₅₀) values of L. siceraria hydrolysates (LSH) and C. moschata hydrolysates (CMH) were 70 ± 6.2 and 135.6 ± 4.5 μg/mL in viable count method and 73.2 ± 2.9 and 122.9 ± 3.2 μg/mL in turbidity method, respectively, against A. baumannii. Based on the above findings, seed protein hydrolysates of these plants may be considered as nutritional food and functional antimicrobial agents in food system.     

Development of a High-Performance Thin-Layer Chromatographic Method for Quantification of Cucurbitacin B in Bottle Gourd (Lagenaria siceraria) for Quality Control

JPC – Journal of Planar Chromatography – Modern TLC - Bottle gourd (Lagenaria siceraria (Molina) Standl.) is an important vegetable cucurbit cultivated in the warmer parts of the world....     

Optimization of microwave and infrared drying process of nettle leaves using design of experiments

Journal of Thermal Analysis and Calorimetry - Optimization of microwave and infrared drying processes of nettle leaves was investigated using dependent variables of drying time and phenolic...     

造纸污泥薄层干燥实验及动力学模型分析

通过造纸污泥薄层干燥实验,考察了温度对造纸污泥干燥特性的影响,引入薄层干燥模型对污泥干燥动力过程进行模拟。结果表明,泥层越薄和干燥温度越高,污泥干燥的速率就越快,当干燥温度从80℃上升到160℃时,相对应的最大干燥速率从0.008g/(g·min)上升到0.030g/(g·min);Modified page模型描述了薄层造纸污泥在烘箱中的干燥过程,应用Fick扩散模型,薄层造纸污泥在干燥温度为80℃～160℃时,有效扩散系数为2.2×10^-10m²/s~3.96×10^-10m²/s。通过Arrhenius方程建立温度和有效扩散系数之间的关系,得出水分扩散的活化能为9.435kJ/mol。     

Investigation of linear alkylbenzene synthesis using nanotitania-supported Dawson heteropolyacid as catalyst by statistical design approaches

Research on Chemical Intermediates - Alkylation of benzene with 1-decene for production of linear alkylbenzene in the presence of nanotitania (n-TiO2)-supported Dawson heteropolyacids was studied....     

Optimization of Pb(II) biosorption by Robinia tree leaves using statistical design of experiments

The present study introduces Robinia tree leaves as a novel and efficient biosorbent for removing Pb(II) from aqueous solutions. In order to reduce the large number of experiments and find the highest removal efficiency of Pb(II), a set of full 2(3) factorial design with two blocks were performed in duplicate (16 experiments). In all experiments, the contact time was fixed at 25 min. The main interaction effects of the three factors including sorbent mass, pH and initial concentration of metal-ion were considered. By using Student's t-test and analysis of variances (ANOVA), the main factors, which had the highest effect on the removal process, were identified. Twenty-six experiments were designed according to Doehlert response surface design to obtain a mathematical model describing functional relationship between response and main independent variables. The most suitable regression model, that fitted the experimental data extremely well, was chosen according to the lack-of-fit-test and adjusted R(2) value. Finally, after checking for possible outliers, the optimum conditions for maximum removal of Pb(II) from aqueous solution were obtained. The best conditions were calculated to be as: initial concentration of Pb(II)=40 mg L(-1), pH 4.6 and concentration of sorbet equal to 27.3 g L(-1).     

The experimental study and modelling the drying kinetics of mussels using ultrasound assisted vacuum drying

In the present study, chemical compositions, drying kinetics, quality parameters and energy consumptions for mediterranean or black mussel (Mytilus galloprovincialis) subjected to ultrasound assisted vacuum drying (UAVD) were analyzed between the range of 50–70 ​°C. During drying only falling rate periods were observed. Obtained conclusions demonstrated that the moisture content and drying rate were influenced by the ultrasound assisted vacuum drying method and the drying air temperature. The ultrasound assisted vacuum drying shortened the drying period and increased the effective moisture diffusivity (D_eff). Drying led to a considerable increasing of protein and fat content. Six well-known thin layer drying models were compared with regards to coefficients of determination. The Alibas model was selected as the best one. The activation energy was calculated as 3.80 ​kW/kg. High “L1" and low "ΔE" values were obtained for dried mussels. Using of ultrasound assisted vacuum drying technique resulted in very low energy consumption.     

Single-molecule, single-particle approaches for exploring the structure and kinetics of nanocatalysts

In this Article, we focus on the in situ observation of photochemical reactions on individual nanoobjects of solid catalysts using single-molecule, single-particle fluorescence spectroscopy. The use of high-resolution imaging techniques with suitable fluorogenic probes enables us to determine the location of the catalytically active sites that are related to the structural heterogeneities on the surface of the solid catalyst and the temporal fluctuation of photochemical reactivity. Furthermore, we present the real-time observation of metastable gold nanoclusters in polymer matrices at the single-cluster level. This Article encourages readers to explore the nanoworld in terms of practical applications in many fields such as fundamental physics and chemistry.     

Criteria for the dilatometric analysis to determine the transformation kinetics during continuous heating

Journal of Thermal Analysis and Calorimetry - A method was established to determine the amount of austenite formed, by stages, in a low-carbon steel through dilatometric analysis. Based on length...     

D-optimal design of DSC experiments for nth order kinetics

D-optimal experimental designs are developed for differential scanning calorimetry experiments conducted under non-isothermal, constant heating modes under the assumption that the kinetics can be described by an nth order model. Two separate cases are considered: single-scan experiments in which the entire rate of reaction versus temperature curve is available, albeit only at selected points, and multiple-scan experiments in which only the temperature at the maximum in the DSC curve is available but it is known at several heating rates. For the single-scan experiment, the D-optimal heating rate and critical extents of reaction where the data should be analyzed are determined. For the multiple-scan experiment the three D-optimal heating rates are determined. For both cases, a hypothetical example is given which illustrates the success and limitations of this approach.     

Comparison and improvement of commonly applied statistical approaches for identification of plant species from IR spectra

Fourier transform infrared spectroscopy (FTIR) has been studied many times in the context of identification of plant, fungal and bacterial species. Infrared spectra are commonly analyzed using multivariate statistical methods such as cluster analysis (CA), principal component analysis (PCA), partial least squares analysis (PLS) and discriminant analysis (DA). In this study, a univariate statistical method for analysis of variance (ANOVA) was used to reduce the number of variables before applying the multivariate methods. Analyzing variables using ANOVA or a combination of ANOVA with CA produced better results. Here, experiments were carried out by performing ANOVA using the first derivative of the spectra instead of the original spectra or its second derivative because using the first‐derivative variables led to improved distinction between species. Different results were obtained by applying different validation methods. The leave‐one‐out validation method gave higher results than the validation‐with‐training and validation sample sets, thus indicating the non‐objectivity of the leave‐one‐out validation method. Copyright © 2010 John Wiley & Sons, Ltd.     

Limit of detection and limit of determination: Application of different statistical approaches to an illustrative example of residue analysis

Summary For the analysis of organochlorine residues in sediments, sewage sludge and industrial waste water a new combination of well-known residue analytical steps has proved useful. Fortification experiments extensively performed should enable the estimation of limits of detection (LDC) and limits of determination (LDM) for 35 organochlorine compounds. The statistical evaluation of the analytical results showed, however, that with just 5 blank analyses and 5 analyses at a reasonable low fortification level, LDC and LDM estimates could be calculated which appeared to be exact enough for most purposes of daily residue analytical work.

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Nachweis- und Bestimmungsgrenze: Anwendung verschiedener statistischer Konzepte auf ein praktisches Beispiel der Rückstandsanalyse

     

Experimental investigation of the performance of an indirect-mode natural convection solar dryer for drying fenugreek leaves

The main objectives of the present work are firstly to study and compare the thin layer drying characteristics of fenugreek leaves by open sun and solar drying methods, and secondly to select a mathematical model for describing the drying process under open sun and solar drying of fenugreek leaves using thin layer drying models available in the literature. Eight thin layer drying models, which are empirical or semi-empirical, are tested to validate the experimental data. A non-linear regression analysis using a statistical computer programme is used to evaluate the constants of the models. The performance of the models was investigated by comparing the coefficient of correlation (R ²), sum of squares error (SSE), mean squared error (MSE) and root mean square error (RMSE) between observed and predicted moisture ratios. According to results, Wang and Singh model gives the highest value of R ² and the lowest values of SSE, MSE and RMSE. Therefore, Wang and Singh model is the best for explaining drying behaviour of fenugreek leaves in both the trays inside the solar dryer and in the tray under open sun.     

A statistical study of the kinetics of phase separation for a liquid crystalline mixture

The kinetics of cholesteric phase growth during the phase separation of an isotropic liquid crystalline mixture was studied by polarizing optical microscopy within the framework of the thermodynamics of irreversible processes. The rules governing time-dependent changes in the parameters of the statistical droplet size distribution of the cholesteric phase were determined. The influence of the thickness of the liquid crystalline mixture layer on the size of the droplets formed was studied.     

Photon transmission technique for studying swelling and drying kinetics of heterogeneous gels formed with various cross-linker contents

Bifunctional polytetrahydrofuran (PTHF) macromonomer was synthesized by the termination of living polymerization of tetrahydrofuran (THF) initiated by triflic anhydride and subsequent termination by sodium methacrylate. PTHF macromonomer thus prepared was copolymerized with methyl methacrylate (MMA) by free radical polymerization to yield networks in various cross-linker densities. These PTHF-PMMA gels were used for swelling experiments in chloroform vapor. Drying processes were monitored after removing the gels from the solvent vapor. Photon transmission from PTHF-PMMA gels was monitored during swelling and drying processes using UV-visible spectrophotometer. Transmitted light intensities, I_tr from these gels decreased when they are subjected to chloroform vapor. Decrease in I_tr was attributed to the heterogeneous lattice structure of PTHF-PMMA gels which appeared during swelling. Decrease in I_tr was modeled using Li-Tanaka equation from which time constants, τ₁ and τ^′₁ and cooperative diffusion coefficients, D₀ and D^′₀ were determined. Increase in I_tr after removing of vapor from the cell was observed and attributed to the decrease in heterogenity of lattice structures during drying of the corresponding gels. Time constants, τ₂ for drying processes were also determined.     

Coulometric investigation of the conditions for drying bauxites for chemical analysis

In order to dry a bauxite sample to constant weight for the determination of alumina content, the following procedure is recommended. The sample should be placed in a small flat weighing bottle and heated at 105-110 degrees for 5 hr in a dried atmosphere, then cooled in a desiccator containing magnesium perchlorate. After weighing, it should be reheated at 105-110 degrees for 40-60 min then cooled and weighed under the same conditions to ensure it has attained constant weight.     

Designing compound subsets: comparison of random and rational approaches using statistical simulation

Compound subsets, which may be screened where it is not feasible or desirable to screen all available compounds, may be designed using rational or random selection. Literature on the relative performance of random versus rational selection reports conflicting observations, possibly because some random subsets might be more representative than others and perform better than subsets designed by rational means, or vice versa. In order to address this likelihood, we simulated a large number of rationally designed subsets for evaluation against an equally large number of randomly generated subsets. We found that our rationally designed subsets give higher mean hit rates compared to those of the random ones. We also compared subsets comprising random plates with subsets of random compounds and found that, while the mean hit rate of both is the same, the former demonstrates more variation in the hit rate. The choice of compound file, rational subset method, and ratio of the subset size to the compound file size are key factors in the relative performance of random and rational selection, and statistical simulation is a viable way to identify the selection approach appropriate for a subset.