Application of Fourier transform Raman spectroscopy for prediction of bitterness of peptides

The potential application of Fourier transform (FT) Raman spectroscopy to predict the bitterness of peptides was investigated. FT-Raman spectra were measured for the amino acid Phe and 9 synthetic di-, tri-, and tetra peptides composed of Phe, Gly, and Pro. Partial least squares regression (PLS)-1 analysis was applied to correlate the FT-Raman spectra with bitterness intensity values (R(caf) and log 1/T) reported in the literature. Using full cross-validation, Model 1 based on the single spectral data set for the nine peptides yielded a high correlation coefficient for calibration (R = 0.99), but a low correlation coefficient for prediction (R = 0.56). Two models were constructed using the data sets including replicate spectra for the calibrations and were validated using full cross-validation. Using leave-one-sample-set-out calibrations, Model 2, which was developed with the data for the peptides as well as Phe, yielded a low correlation coefficient (R = 0.533) for the prediction of the bitterness, while Model 3 developed with only the peptide data provided better correlation coefficients (R = 0.807 and 0.724 for R(caf) and log 1/T values, respectively). The correlation coefficients for prediction were 0.975 (R(caf) values) and 0.874 (log 1/T values) for Model 4, which was developed using subtracted spectral data (spectra of peptides with higher R(caf) values minus spectra of peptides with lower R(caf) values). Examination of the PLS regression coefficients at wavenumbers most highly correlated with bitterness revealed the importance of hydrophobicity and peptide length on bitterness. This study indicates the potential of FT-Raman spectroscopy as a useful tool for predicting bitterness of peptides and amino acids.     

Effects of annealing on the structural and mechanical properties of electrospun polymeric nanofibres

Biodegradable polymeric nanofibres produced by electrospinning have been used as scaffolds for tissue engineering. Before these nanofibrous scaffolds can be implanted into the human body, it is important to know if the individual nanofibres are strong enough to withstand the forces exerted by the cells as they grow and migrate on the scaffold. However, due to the small size of the nanofibres, it is a challenge to characterize the mechanical properties of individual nanofibres. Therefore, we aim to mechanically characterize a single nanofibre using both a tensile test and a nanoscale three-point bend test. As some scaffolds may be heat-treated by annealing to enhance the stiffness and strength of the nanofibres, we also investigate the effects of annealing on the structural and mechanical properties of single nanofibres. The material properties of as-spun and annealed nanofibres were studied using differential scanning calorimetry and atomic force microscopy. Annealing was found to increase the Young's modulus of the nanofibre mainly due to the increase in crystallinity and the change in morphology from a purely fibrillar structure to a mixture of fibrillar and nano-granular structure with enhanced interfibrillar bonding.     

Effects of Kudoa spores,endogenous protease activity and frozen storage on cooked texture of minced Pacific hake (Merluccius productus)

The effects of Kudoa infection of Pacific hake (Merluccius productus) on endogenous protease activity and on cooked mince texture were investigated. Texture was significantly (p < 0.05) negatively correlated with spore counts as well as protease activity. Soft texture (maximum force <150 g) was observed in fish with 10⁴–10⁶Kudoa thyrsites spores g⁻¹ mince, compared to 10⁵–10⁸K. paniformis spores g⁻¹ mince, suggesting that especially for fish having lower infection levels, K. thyrsites may have a greater impact than K. paniformis on Pacific hake quality. Pre-incubation for 15 min at 52 °C prior to cooking resulted in softer texture in some samples due to endogenous proteolytic action. This pre-incubation effect was not consistently observed in fish held 6 months or longer at −25 °C or after freeze-thaw cycling, which may be explained by an opposing toughening effect attributed to protein denaturation and aggregation during prolonged or abusive frozen storage.     

The dynamics of culture, organisational culture and change

The interface between cultural anthropology, cross-cultural psychology, cultural psychology and indigenous psychology provides a rich context for examining recent developments within the field of organisational culture, both from a societal (national) and a cross-cultural perspective. It is argued in this paper that cultural patterns in society impact deeply on cultural patterns in organisations. In other words, organisational culture reflects the way in which the societal context shapes the organisational context, which in turn moulds the beliefs, attitudes and behaviour of its members — individuals and groups. It is further posited that organisational cultural and societal culture recursively mirror one another. The complexity of the interdependence between societal culture and organisational culture will be traced, drawing on the evolving nature of the construct culture within the traditions of anthropology, cross-cultural psychology, indigenous psychology and organisational psychology. The hidden source of cultural elements embedded in the organisational domain will be examined from the perspective of an appreciation of diversity and a recognition of the need to support and encourage the variations that add to our creativity as well astosystem/organisational effectiveness.     

The removal of Cu(II) and Co(II) from aqueous solutions using cross-linked chitosan--evaluation by the factorial design methodology

A 2(3) factorial design was employed to evaluate the quantitative removal of Cu(II) and Co(II) on glutaraldehyde-cross-linked chitosan from kinetic isotherms, using chitosan masses of 100 and 300mg and temperatures of 25 and 35 degrees C. The adsorption parameters were analyzed statistically using modeling polynomial equations and a cumulative normal probability plot. The results indicated the higher quantitative preference of the chitosan for Cu(II) in relation to Co(II). Increasing the chitosan mass decreases the adsorption/mass ratio (mol g(-1)) for both metals. The principal effect of the temperature did not show statistical importance. The adsorption thermodynamic parameters, namely Delta(ads)H, Delta(ads)G and Delta(ads)S, were determined. Exothermic and endothermic results were found in relation to a specific factorial design experiment. A comparison of Delta(ads)H values was made in relation to some metal-adsorbent interactions in literature. It is suggested that the adsorption thermodynamic parameters are determined by the influence of the principal and interactive experimental parameters and not by the temperature changes alone.     

Effects of ultrasound on structural and physical properties of soy protein isolate (SPI) dispersions

The effects of low-frequency (20 kHz) ultrasonication at varying power (200, 400 or 600 W) and time (15 or 30 min) on functional and structural properties of reconstituted soy protein isolate (SPI) dispersions were examined. Ultrasonic treatments reduced both the storage modulus and loss modulus of SPI dispersions and formed more viscous SPI dispersions (fluid character). Moreover, ultrasound treatment significantly decreased the consistency coefficients and increased the flow behaviour index of SPI dispersions. Scanning electron microscopy of lyophilized ultrasonicated SPI showed different microstructure with larger aggregates compared to non-treated SPI. No significant change was observed in the protein electrophoretic patterns by SDS-PAGE. However, free sulfhydryl content, surface hydrophobicity and protein solubility of SPI dispersions were all increased with ultrasonic treatment. Differences in solubility profiles in the presence versus absence of denaturing (0.5% sodium dodecyl sulphate and 6 M urea) and reducing (mercaptoethanol) agents suggested a decrease in non-covalent interactions of SPI in dispersion after ultrasonic treatment. Secondary structure analysis by circular dichroism indicated lower α-helix and random coil in SPI treated at lower power, in contrast to higher α-helix and lower β-sheet in SPI treated with higher power (600 W). In conclusion, under the conditions investigated in this study, ultrasonic treatment resulted in partial unfolding and reduction of intermolecular interactions as demonstrated by increases in free sulfhydryl groups and surface hydrophobicity, leading to improved solubility and fluid character of SPI dispersions, while larger aggregates of ultrasonic-treated SPI in the dry state were formed after lyophilization.     

Detection and Quantification of Chloramphenicol in Milk and Honey Using Molecularly Imprinted Polymers: Canadian Penny‐Based SERS Nano‐Biosensor

We integrated molecularly imprinted polymers with surface‐enhanced Raman spectroscopy (MIPs‐SERS) to develop an innovative nano‐biosensor for the determination of chloramphenicol (CAP) in milk and honey products. Template molecule (CAP), functional monomer (acrylamide), cross‐linking agent (ethylene glycol dimethacrylate), initiator (2,2’‐azobis(isobutyronitrile)), and porogen (methanol) were employed to form MIPs via “dummy” precipitation polymerization. Static and kinetic studies validated the specific selectivity of MIPs toward CAP over nonimprinted polymers (imprinting factor >4). Canadian penny‐based silver nano‐structure was synthesized as SERS‐active substrate for determination of CAP in food matrices. Collected spectra were processed by principal component analysis to differentiate various concentrations of CAP in foods. Partial least squares regression models showed good prediction values (R > 0.9) of actual spiked contents (0, 0.1, 0.5, 1, 5 ppm) of CAP in milk and honey. This developed nano‐biosensor is low cost, requires little sample pretreatment, and can provide reliable detection of trace level of chemical hazards in food systems within a total of 15 min.     

核心筒、隔断和无用空间

迫于日益增加的合作全球化和文化多样性．偏建设计工作室认为需要创造一种新的设计方法才能处理复杂交错的地理、文化和功能。通过几则彼此迥异却相互交织的故事——建筑核心筒、隔断和无用空间及其功能与空间的关联性．建筑师尝试在全球有关普遍性论述的范畴中揭示这些离散的空间的意义。     

Ecological Method for the Synthesis,Characterization and Antimicrobial Effect of Silver Nanoparticles Produced and Stabilized with a Mixture of Mucilage/Proteins Extracted from Flaxseed

Journal of Inorganic and Organometallic Polymers and Materials - A simple and ecologically friendly method was used for the synthesis of mucilage/proteins (M/P) stabilized silver nanoparticles...     

Secreted Extracellular Vesicle Molecular Cargo as a Novel Liquid Biopsy Diagnostics of Central Nervous System Diseases

Secreted extracellular vesicles (EVs) are heterogeneous cell-derived membranous granules which carry a large diversity of molecules and participate in intercellular communication by transferring these molecules to target cells by endocytosis. In the last decade, EVs’ role in several pathological conditions, from etiology to disease progression or therapy evasion, has been consolidated, including in central nervous system (CNS)-related disorders. For this review, we performed a systematic search of original works published, reporting the presence of molecular components expressed in the CNS via EVs, which have been purified from plasma, serum or cerebrospinal fluid. Our aim is to provide a list of molecular EV components that have been identified from both nonpathological conditions and the most common CNS-related disorders. We discuss the methods used to isolate and enrich EVs from specific CNS-cells and the relevance of its components in each disease context.