Evaluation of microbial toxins,trace elements and sensory properties of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis via submerged fermentation

Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B₁, G₁, B₂, G₂, cyclopiazonic acid, fumonisins B₁, B₂, B₃ and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea.     

The effect of segment length on some properties of thermoplastic poly(ester–siloxane)s

A series of novel thermoplastic elastomers, based on poly(dimethylsiloxane) (PDMS) as the soft segment and poly(butylene terephthalate) (PBT) as the hard segment, were synthesized by catalyzed two‐step, melt transesterification reactions of dimethyl terephthalate and methyl esters of carboxypropyl‐terminated poly(dimethylsiloxane)s (M?_n = 550–2170 g mol^?1) with 1,4‐butanediol. The lengths of both the hard and soft segments were varied while the weight ratio of the hard to soft segments in the reaction mixture was maintained constant (57/43). The molecular structure, composition and molecular weights of the poly(ester–siloxane)s were examined by ¹H NMR spectroscopy. The effectiveness of the incorporation of the methyl‐ester‐terminated poly(dimethylsiloxane)s into the copolymer chains was verified by chloroform extraction. The effect of the segment length on the transition temperatures (T_m and T_g) and the thermal and thermo‐oxidative degradation stability, as well as the degree of crystallinity and hardness properties of the synthesized TPESs, were studied. Copyright © 2003 Society of Chemical Industry     

Synthesis of some fumaric acid polyamides from active diester monomers

Summary The solution polycondensation of two active diesters, bis(2,4-dinitrophenyl) fumarate and 1,1-(fumaroyldioxy)bis(benzotriazole), with a series of alphatic and aromatic diamines in N-methyl pyrolidone at room temperature, was investigated. The polycondensation reactions yielded a series of fumaric acids polyamides. The polymers obtained from aliphatic diamines were soluble in trifluroacetic acid and exhibited well-defined melting points. The polymers obtained from aromatic diamines are infusible at temperatures below 300°C but were thermally stable and soluble in dimethylacetamide containing 4% LiC1.     

MALDI Q-TOF CID MS for Diagnostic Ion Screening of Human Milk Oligosaccharide Samples

Human milk oligosaccharides (HMO) represent the bioactive components of human milk, influencing the infant’s gastrointestinal microflora and immune system. Structurally, they represent a highly complex class of analyte, where the main core oligosaccharide structures are built from galactose and N-acetylglucosamine, linked by 1–3 or 1–4 glycosidic linkages and potentially modified with fucose and sialic acid residues. The core structures can be linear or branched. Additional structural complexity in samples can be induced by endogenous exoglycosidase activity or chemical procedures during the sample preparation. Here, we show that using matrix-assisted laser desorption/ionization (MALDI) quadrupole-time-of-flight (Q-TOF) collision-induced dissociation (CID) as a fast screening method, diagnostic structural information about single oligosaccharide components present in a complex mixture can be obtained. According to sequencing data on 14 out of 22 parent ions detected in a single high molecular weight oligosaccharide chromatographic fraction, 20 different oligosaccharide structure types, corresponding to over 30 isomeric oligosaccharide structures and over 100 possible HMO isomers when biosynthetic linkage variations were taken into account, were postulated. For MS/MS data analysis, we used the de novo sequencing approach using diagnostic ion analysis on reduced oligosaccharides by following known biosynthetic rules. Using this approach, de novo characterization has been achieved also for the structures, which could not have been predicted.     

The reliability of CPTu and DMT for the mechanical characterisation of soft tailings

Nowadays, the stability and the safe cover and closure of soft tailings has become one of the most challenging topics in geotechnical and environmental engineering. For appropriate analysis and modelling, geotechnical properties of tailings should be well defined. Due to low strength, viscous nature and poor trafficability, as well as due to the specific geometrical properties of fine particles and pore water chemistry in tailings, different test methods and their modification and improvements must be used for valid and reliable characterisation of tailings. This paper analyses and compares the results of different field test methods, piezocone penetration test (CPTu), flat dilatometer test (DMT) and field vane test (FVT), performed on the red gypsum sludge and complementary laboratory tests. CPTu and DMT measurements were evaluated using procedures developed for soils and the obtained mechanical properties were compared with those measured in the laboratory. The significant distinctions between different test methods and different empirical correlations were analysed taking into account differences in index properties of soils and the red gypsum sludge. Based on analysis, some modifications of conventional empirical correlations were proposed for field tests results interpretation and sludge characterisation. The obtained data also show the advantages and limitations of some conventional methods and prove the need for further development in that field of geotechnical investigation.

     

Prediction of traditionally utilised wheat dough technological quality parameters from Mixolab values: development and evaluation of regression models

The research was conducted with the aim to investigate the possibility of Farinograph, Extensograph and Amylograph values prediction with linear and/or multiple Mixolab regression models. In total, 163 flour samples were divided based on Machalanobis distances into three sets: prediction, validation and external sample set. Determination coefficients ranged from 0.145 to 0.640 for linear regression models and from 0.279 to 0.739 for multiple regression models. Internal and external validation of developed regression models was conducted. Testing of developed models resulted in a high share of samples for which predicted values were out of the ranges of method official reproducibility and a high share of samples for which predicted values were out of the quality level range obtained by analytical measurement. It was concluded that it is impossible to develop applicable regression models for prediction of Farinograph, Extensograph and Amylograph parameters on the basis of Mixolab values from standard protocol.     

Viscoelastic properties of poly(ε‐caprolactone)/clay nanocomposites in solid and in melt state

Viscoelastic properties in solid and in melt state of poly(ε‐caprolactone), PCL, nanocomposites with organomodified clays (Cloisite30B and Cloisite15A) are thoroughly investigated. Although WAXD is insensitive to the difference in the nanocomposites structure, the melt rheology reveals pronounced differences between the two series. Melt yield stress values, obtained from fittings by the Carreau–Yasuda model, are used as a measure of partial exfoliation of the clay. Temperature dependence of the shift factors, used for time–temperature superposition of the modulus curves, yields similar values of the flow activation energies for all the samples. Temperature dependences of the dynamic modulus and loss factor of solid nanocomposites were correlated to the structural differences deduced from the melt rheology. The increase in the storage modulus is compared to the theoretical predictions from the Halpin–Tsai model. The effective aspect ratio obtained from this comparison agrees reasonably with the value estimated from the melt rheology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42896.     

G-quadruplex formation of oligonucleotides containing ALS and FTD related GGGGCC repeat

A largely increased number of GGGGCC repeats located in the non-coding region of C9orf72 gene have been identified as the leading cause of two related neurological disorders, familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We examined G-quadruplex forming ability of GGGGCCrepeat containing oligonucleotides with four guanine tracts chosen as the smallest possible model to form a unimolecular G-quadruplex. These oligonucleotides are readily to folded into G-quadruplexes in the presence of K⁺ ions. However, the formation of multiple structures makes structural analysis challenging and time consuming. We observed that flanking sequences on 5'- and 3'-ends as well as mutations of loop residues have a profound effect on folding. Sequence d[(G₄C₂)₃G₄] was chosen for further scrutiny and optimization of nuclear magnetic resonance (NMR) spectroscopic properties with dG to 8Br-dG substitutions at specific positions in the sequence under different folding conditions. Expectedly, folding into desired predominant topology is facilitated when substituted residue adopted a syn conformation in the naturally-occurring structure. Single dG to 8Br-dG substitution at position 21 and fine tuning of folding conditions facilitate folding of d[(G₄C₂)₃GG^BrGG] into (mostly) a single G-quadruplex, and thus enable determination of its high-resolution structure by high-field NMR.

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