An antimicrobial peptide screened from casein hydrolyzate by Saccharomyces cerevisiae cell membrane affinity method

A Saccharomyces cerevisiae cell membrane affinity screening method was developed to separate targeted antimicrobial peptides from the pepsin hydrolyzate of bovine casein. S. cerevisiae cell membranes were first immobilized on the surface of the silica gel to construct an affinity binding medium. A membrane-binding fraction was successfully screened by comparing the RP-HPLC fingerprint chromatograms of the hydrolyzate before and after adsorption with the adsorption medium. The amino acid sequence of the peptide was identified as LRLKKYKVPQL with the use of a matrix-assisted laser desorption/ionisation quadrupole time-of-flight tandem mass spectrometer. The sequence corresponded to amino acid residues 99–109 of bovine α_S1-casein. The results indicated that it is feasible to target screen antimicrobial peptides from protein hydrolyzate using S. cerevisiae cell membranes. The influences of thermal treatment, pH, ions, and enzymes on the activity of the purified peptide were also determined. The activity of the peptide was relatively thermally stable and was pH dependent. It retained more than 90% of its activity in the presence of 15% Na⁺, K⁺ and pepsin. Trypsin, proteinase K, divalent cation Mg²⁺ and Ca²⁺ reduced the activity to different extents. The peptide also showed antibacterial effectiveness in fresh pear juice. These observations provide further information on the application of protein-derived antimicrobial peptides in food systems.     

Antilisterial activity and stability of nanovesicle-encapsulated antimicrobial peptide P34 in milk

Bacillus sp. P34, a strain isolated from aquatic environments of Brazilian Amazon basin, produces a bacteriocin-like substance (BLS) which was encapsulated in nanovesicles prepared from partially purified soy lecithin. The efficiency of free and encapsulated BLS P34 to control the development of L. monocytogenes and maintenance of antimicrobial activity was assessed over time in milk. The antimicrobial activity of free and encapsulated BLS P34 decreased approximately 50% after 4 days of storage (<4 °C) in skim and whole milk. After this period there was not significant loss of activity up to 21 days. The viable counts of Listeria monocytogenes in skim and whole milk containing 3200 AU/ml of free or encapsulated BLS P34 were always lower than those observed in controls without bacteriocin at both 30 °C and 7 °C. At 1600 AU/ml concentration, free and encapsulated BLS P34 were inhibitory to L. monocytogenes in skim milk, when compared with the control at 7 days. Nanovesicle-encapsulated and free BLS P34 shows potential use as biopreservative for application in milk-derived products.     

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank has been considered. Two modes of the process has been studied, one with a constant degree of separation in the membrane module and the other with a constant concentration of impurities in the stream directed to the receiver tank. The degree of removal and the time of the process have been calculated. It has been shown that the second mode is somewhat more cost-effective because of the lack of mixing of streams with different concentrations and the absence of the lost work of separation.     

Application of novel ANFIS-PSO approach to predict asphaltene precipitation

Asphaltene precipitation is known as one of the challenging problems in petroleum industries which have significant effects on production such as formation damage and wellbore plugging. To solve this problem, calculation of precipitated asphaltene becomes highlighted so in the present study a novel approach is proposed based on ANFIS algorithm to estimate precipitated asphaltene in terms of dilution ration, carbon number of precipitants and temperature. The particle swarm optimization (PSO) method is applied to optimize ANFIS algorithm parameters. The proposed model was evaluated based on statistical parameters and the calculated R², AARD and RMSE for the total data are 0.90309, 9.4908 and 7.9468. They showed the predicting algorithm performed in acceptable manner so a high accurate and simple tool was proposed to predict the precipitated asphaltene as function of Dilution ration, temperature and carbon number of precipitants.     

Rapid and specific sensing of tetracycline in food using a novel upconversion aptasensor

Rare earth-doped upconversion nanoparticles (UCNPs) have a promising potential in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This study developed a novel and sensitive aptamer-based UCNPs (NaY_0.48Gd_0.3F₄:Yb_0.2, Ho_0.02) biosensor for sensing tetracycline (TET) in foodstuffs. The aptamer-magnetic nanoparticles (aptamer-MNPs) and the complementary DNA-UCNPs (cDNA-UCNPs) conjugates were prepared and used as the capture and signal probes, respectively. They formed the complex of MNPs-aptamer-cDNA-UCNPs with complete binding. With TET addition, the aptamer preferentially bound with TET and caused the dissociation of some cDNA; and the liberation of some cDNA-UCNPs. This led to a decreased fluorescent signal on the surface of MNPs. Under the optimal conditions, a wide linear detection range from 0.01 to 100 ng/mL was achieved, with a limit of detection of 0.0062 ng/mL, for detection of TET. The proposed method was successfully applied to measure TET in contaminated samples. Results showed that the proposed UCNPs biosensor offers an efficient, specific, and simple approach for the detection of TET in food, and has high potential for food safety and quality control.     

Application of Fuzzy C-means algorithm as a novel approach to forecast gas density in different conditions

One of the dominant parameters in accurate calculation and forecasting processes gas industries is accurate estimation of gas properties. The gas density is known as an effective parameter in gas processes calculations which affected by pressure and temperature. In the present paper, the Fuzzy c-means (FCM) algorithm is utilized as a novel predictive tool to estimate gas density as function of molecular weight, critical pressure and critical temperature of gas, pressure and temperature. In the purpose of training and testing of proposed FCM algorithm, a total number of 1240 measured data were gathered from reliable sources. The outputs of model and experimental data comparisons showed the great agreement between them such that the coefficients of determination for training and testing datasets were determined as 0.9982 and 0.9903 respectively. According to the obtained results from the graphical and statistical comparisons it can be concluded that the FCM algorithm has great ability and enough accuracy in prediction of gas density.     

New approach to the characterization of ion-exchange membranes using a set of model parameters

An extended three-wire model of the conductivity of ion-exchange membranes is proposed. The model includes a set of three-wire model equations supplemented with coupling equations between three-wire model parameters and the parameters of a microheterogeneous model. To calculate the complete set of parameters for evaluating the structural inhomogeneity of a membrane and calculating its effective electrotransport properties, it is necessary and sufficient to get only the concentration dependence of the specific conductivity of the membrane, which simplifies the characterization procedure. The model was verified based on independent experimental data and the calculations of transport-structural parameters with the use of the microheterogeneous model. It was found that the proposed model approach makes it possible to obtain a reliable combination of structural parameters to characterize the volume fractions of conductive phases and their mutual arrangement in the ion exchange material peculiar to the membrane test sample.     

A highly sensitive method for quantifying gallocatechin gallate and its epimer using a catechin-specific peptide

We have developed a method for quantifying gallocatechin gallate (GCg) and epigallocatechin gallate (EGCg) using a catechin-binding peptide (part of the 67-kDa laminin receptor). Using micro titer plates, we investigated various conditions, including the quantifiable range of EGCg concentrations, the optimal concentration of the catechin-binding peptide, and the optimal reaction conditions. In this microplate assay, after each well was coated with bovine serum albumin, sample containing GCg and EGCg was added at pH 8.0, and allowed to stand at 37 °C for 2 h. After washing, biotinylated-peptide solution was added at 1 μg mL^?1 and allowed to react for 1 h at 37 °C. Each well was added with streptavidin–horseradish peroxidase conjugate, followed by chromogenic reaction for 25 min at room temperature. After the reaction, absorbance was measured at 405 nm. Our method is capable of quantifying EGCg in the range of approximately 0.1–2.0 mg L^?1 with a high degree of sensitivity and a high correlation (R² = 0.98) between EGCg concentration and absorbance. The method was specific to GCg and EGCg and seems capable of estimating GCg and EGCg contents in the presence of other catechin compounds. The method is simple and highly sensitive for quantitative GCg and EGCg measurement that requires no special equipment or operation and can measure multiple samples simultaneously.     

Modeling of precipitated asphaltene using the ANFIS approach

Asphaltene precipitation is introduced as a seriously problematic issue in the petroleum reservoirs that causes filling porosity of rocks and reduction of oil production. Hence, estimating the amount of precipitated asphaltene has huge importance in preventing the deposition of asphaltene. The present study was done to estimate the precipitated asphaltene as a function of temperature, dilution ratio, and molecular weight of different n-alkanes using adaptive neuro-fuzzy inference system (ANFIS). Moreover, another new scaling model was also developed to compare with the ANFIS model. In addition, these two developed models have been compared with previously developed correlations. The obtained values of R² for the ANFIS and scaling models were 0.9912 and 0.9862, respectively. These tools are simple to use and can be used as an accurate approximation of the precipitated asphaltene as a function of temperature, dilution ratio, and molecular weight of different n-alkanes.     

A novel MLP approach for estimating asphaltene content of crude oil

ABSTRACT

Asphaltene is considering to be the most problematic part of oil that causes pipe plugging, permeability reduction, and ultimately loss of production through its separation process from oil body as result of any thermodynamic change. Its weight fraction is one of key inputs to any asphaltene related modeling, which requires an expensive and time consuming experimental procedure. In this research, for the first time a novel MLP-ANN structure is proposed to predict this critical parameter at wide range of operational conditions, with satisfactory precision. A dataset of over 300 experimental data was gathered from open literature and used to train and test the proposed construct. The results show network great performance and therefore, can be used as a universal tool to provide input for any asphaltene-related modeling, with assurance.     

Applying Fuzzy c-means approach as a novel method for prediction of interfacial tension between carbon dioxide and hydrocarbons

The worldwide demand for energy increases and also the price of crude oil increases so these reasons have been caused the searchers have motivated to investigate enhanced of oil recovery (EOR) processes. The carbon dioxide injection is recognized as one of the favorable approaches of EOR because of high displacement efficiency, environmentally aspects and lower cost. The Interfacial tension between crude oil and carbon dioxide is known as one of the critical factors which affect the performance of injection. The main objective of the present investigation is development of Fuzzy c-means (FCM) approach as novel method to estimate interfacial tension between carbon dioxide and hydrocarbons as function of pressure, temperature, liquid and gas densities and molecular weight of alkane. The performance of predicting model was evaluated statistically and graphically and the results confirmed the ability of the model to predict interfacial tension between carbon dioxide and hydrocarbons.     

Separation of CO2 from CH4 using a synthesized Pebax-1657/ZIF-7 mixed matrix membrane

In this study, ZIF-7 nanoparticles were first synthesized and then incorporated into polyether-block-amide (Pebax-1657) matrix with different loadings to prepare mixed matrix membranes. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses were employed to recognize crystalline structure and chemical bonds variations of the ZIF-7 nanoparticles, respectively. Morphology of the membrane exhibited that the best performance was observed using FESEM analysis. The CO₂ and CH₄ permeation experiments were carried out at temperature and pressure of 30°C and 2.5 bar, respectively. The gas permeation results indicated that the mixed matrix membranes have higher efficiencies for CO₂/CH₄ separation compared with the neat membranes.     

Utilization of Grid partitioning based Fuzzy inference system approach as a novel method to estimate solubility of hydrocarbons in carbon dioxide

Recently due to increasing demand for energy and declination of oil reservoir the researchers have been encouraged to investigate the enhancement of oil recovery (EOR) approaches. One of popular and wide applicable processes in EOR is carbon dioxide injection which is attractive for researchers and industries due to environmentally aspects, good efficiency in displacement and low cost. The carbon dioxide injection causes the hydrocarbons extracted from crude oil so the solubility of hydrocarbon in carbon dioxide which is one of the critical parameters affects this phenomenon becomes interesting topic for researchers. In the present work Grid partitioning based Fuzzy inference system approach as a new method for prediction of solubility of hydrocarbons in carbon dioxide as function of temperature, pressure and carbon number of alkane was applied. To show the accuracy of the model the coefficients of determination were determined as 0.9902 and 0.9584 for training and testing phases respectively.     

用OFA-2石油荧光分析仪测定钻井液添加剂荧光的方法

人们在降低钻井液添加剂的荧光时存在着误区，一是向钻井液添加剂中加入荧光猝灭剂，二是以牺牲钻井液添加剂中的有效成分为代价降低其荧光级别。介绍了用OFA-2石油荧光分析仪测定钻井液添加剂荧光的方法。该方法能够检测轻质油、凝析油、煤成油，反映各种原油样品的二维荧光全貌，又能实现真正意义上的较准确定量和排除钻井液添加剂荧光的干扰，是一种与目前地质荧光录井要求完全吻合的定量测定钻井液添加剂荧光的方法。     

Crude biodiesel refining using membrane ultra-filtration process: An environmentally benign process

Ceramic membrane separation system was developed to simultaneously remove free glycerol and soap from crude biodiesel. Crude biodiesel produced was ultra-filtered by multi-channel tubular membrane of the pore size of 0.05 μm. The effects of process parameters: transmembrane pressure (TMP, bar), temperature (°C) and flow rate (L/min) on the membrane system were evaluated. The process parameters were then optimized using Central Composite Design (CCD) coupled with Response Surface Methodology (RSM). The best retention coefficients (%R) for free glycerol and soap were 97.5% and 96.6% respectively. Further, the physical properties measured were comparable to those obtained in ASTMD6751-03 and EN14214 standards.     

A novel approach for simultaneous determination of E/Z-fluoxastrobins in vegetables and fruits by UHPLC-DAD

In this work, a novel analytical method was established for simultaneous determination of E-fluoxastrobin and Z-fluoxastrobin in vegetables and fruits. After extracted by acetonitrile, the samples were cleansing with dispersive solid liquid extraction (d-SLE) process, and analyzed by ultra high performance liquid chromatography coupled to diode array detection (UHPLC-DAD). The effectiveness of the optimized method was validated by determining the linearity (R² > 0.99), sensitivity (limits of quantification of 30 μg/kg), recovery (71.3–113.2%), and precision (relative standard deviations, RSDs ≤ 13.9%) in eight vegetable and fruit samples. The results suggested that this method was simple, reliable, and feasible to determine the residues of E-fluoxastrobin and Z-fluoxastrobin in vegetable and fruit samples, which could be further applied to 160 various vegetable and fruit samples.     

Vapor-phase membrane concentration of bioethanol and biobutanol using hydrophobic membranes based on glassy polymers

Pervaporation and vapor-phase membrane separation methods for the recovery of bioalcohols from dilute aqueous solutions have been critically compared. The importance of taking into account the liquid–vapor equilibrium diagram in studies on the separation of binary aqueous–alcoholic liquid media by these methods has been shown. Previously published experimental data on the transport of water, ethanol, and n-butanol vapors in hydrophobic membranes based on the glassy polymers poly(vinyltrimethylsilane) (PVTMS), poly(1-trimethylsilyl-1-propyne) (PTMSP), and poly(4-methyl-1-pentyne) (PMP) have been analyzed. Schemes of butanol and ethanol recovery by the vapor-phase membrane separation process from fermentation broths for the cases of application of water-selective and alcohol-selective membranes have been presented, as well as the results of mathematical simulation of the process and assessment of energy consumption.     

Inhibition of foodborne pathogens by Hf-1, a novel antibacterial peptide from the larvae of the housefly (Musca domestica) in medium and orange juice

Antibacterial molecules from edible insects may serve as a potentially significant group of food preservatives. Hf-1, a novel peptide from larvae of housefly (Musca domestica) with molecular weight approximately 8.0 KD, inhibited food pathogens Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27553, Salmonella typhimurium 50013, Shigella dysenteriae 51302, Staphylococcus aureus 6538 and Bacillus subtilis 9372 with MIC ranging from 18 to 72 μg/ml. The presence of EDTA can enhance Hf-1 activity against Gram-negative bacteria. Hf-1 was bactericidal in orange juice, showing an antibacterial activity approximately equivalent to sodium benzoate. The mode of action of Hf-1 involved decreasing the cell surface hydrophobicity and damaging the cell membrane. The results suggested Hf-1 has the potential to be used as the food preservative.     

A novel hybrid material based on polytrimethylsilylpropyne and hypercrosslinked polystyrene for membrane gas separation and thermopervaporation

To improve the membrane permeability and separation properties in gas separation processes and thermopervaporative (TPV) recovery of butanol from model fermentation mixtures, hybrid membranes based on polymers with an extremely high free fractional volume—polytrimethylsilylpropyne (PTMSP) and hypercrosslinked polystyrene (HCL-PS)—have been first prepared and experimentally studied. The composite membranes have been fabricated using the commercial sorbent Purolite Macronet MN-200 exhibiting high sorption capacity for organic solvents. It has been found that in the hybrid membranes, HCL-PS sorbent particles are nonuniformly distributed throughout the volume: they are located in the surface layer of the membrane. It has been shown that the introduction of a small amount of a modifying component (0.5–1.0 wt %) into the PTMSP matrix improves the time stability of transport properties and increase by a factor of 1.5–2 the permeability coefficients of the material to light gases (N₂, O₂, CO₂, CH₄) and butane vapor. It has been found that hybrid PTMSP/HCL-PS membranes have higher separation factors than those of PTMSP membranes in the TPV separation of a butanol/water binary mixture.