Variation in catechin contents in relation to quality of ‘Huang Zhi Xiang’ Oolong tea (Camellia sinensis) at various growing altitudes and seasons

The variations in the contents of catechins and phenolic compounds in relation to the quality scores (QS) and taste scores (TS) in the ‘Huang Zhi Xiang’ Oolong tea grown in different seasons and at different altitudes were determined. The study demonstrated that the contents of (−)-epigallocatechin gallate (EGCG), catechin gallate (CG), and total catechins (TC) in the Oolong teas grown at a high altitude were significantly higher than those grown at a low altitude. Furthermore, the contents of EGCG, CG, and TC in the autumn tea were significantly higher than those from the spring tea grown at a low altitude. However, no significant differences in the contents of EGCG, CG, and TC were observed between the spring and autumn teas grown at a high altitude. In addition, the contents of (−)-epigallocatechin (EGC), (+)-catechin (C), (−)-gallocatechin (GC), and simple catechins (SC) in the spring tea leaves were significantly higher than those in the autumn tea leaves grown at a low altitude, but they were not significantly different from those in the autumn tea leaves grown at a high altitude. The contents of EGCG, CG, and TC in the Oolong teas were positively and significantly correlated to the taste score (TS) and quality score (QS) of the Oolong tea. Thus, the contents of EGCG, CG, and TC could be the important quality parameters of the ‘Huang Zhi Xiang’ Oolong tea. This work suggested that the production of the ‘Huang Zhi Xiang’ Oolong tea grown at low altitudes should utilize the autumn tea leaves while the production of Oolong tea grown at high altitudes can use both the spring and autumn tea leaves.     

Refining the Prediction of Potential Malt Fermentability by Including an Assessment of Limit Dextrinase Thermostability and Additional Measures of Malt Modification,Using Two Different Methods for Multivariate Model Development

Prediction of malt fermentability (apparent attenuation limit — AAL) by measurement of the diastatic power enzymes (DPE), α‐amylase, total limit dextrinase, total β‐amylase, β‐amylase thermostability, and the Kolbach index (KI or free amino nitrogen — FAN) is superior to the conventional use of diastatic power (DP) alone. The thermostability of β‐amylase is known to be an important factor in determining fermentability, thus the thermostability of the other relatively thermolabile enzyme, limit dextrinase, was investigated to determine if it was also useful in predicting fermentability. To facilitate this aim, methods were developed for a rapid and cost efficient assay of both β‐amylase and limit dextrinase thermostability. Internationally important Australian and international malting varieties were compared for their total limit dextrinase and β‐amylase activity and thermostability. Interestingly, the level of limit dextrinase thermostability was observed to be inversely correlated with total limit dextrinase activity. The prediction of malt fermentability was achieved by both forward step‐wise multi‐linear regression (MLR) and the partial least squares (PLS) multivariate model development methods. Both methods produced similar identifications of the parameters predicting wort fermentability at similar levels of predictive power. Both models were substantially better at predicting fermentability than the traditional use of DP on its own. The emphasis of this study was on the identification of predictive factors that can be consistently used in models to predict fermentability, because the model parameter estimates will subtly vary depending on mashing conditions, yeast strain/fermentation conditions and malt source. The application of these multivariate model development methods (PLS and MLR) enabled the identification of further potential fermentability predicting factors. The analyses divided the predictive parameters into those defined by DP enzymes and those associated with modification (KI, FAN, fine/coarse difference, wort β‐glucan and friability). Surprisingly, limit dextrinase thermostability was not a substantial predictor of fermentability, presumably due to its negative correlation with total limit dextrinase activity. The application of these insights in the malting and brewing industries is expected to result in substantial improvements in brewing consistency and enable more specific quality targets for barley breeder's progeny selection cut‐off limits to be more precisely defined.     

New systematic and time-saving procedure to design cup grinding wheels for the application of ultrasonic-assisted grinding

Since glass and ceramic materials have beneficial properties, they have gained more importance in numerous technical applications during the last 30 years. For example, nowadays, ceramics are used as artificial hip joints or as mechanical seals for highest relative speeds. Glass components are used for multitude of optical applications like cameras and reflectors. But besides a lot of advantages, the processing of these materials is very difficult. In particular, this contains the manufacturing of small components like microreactor plates or glass wafers with hundreds of small holes, too. Using ultrasonic-assisted grinding, the treatment can significantly be optimized and higher removal rates can be realized. For the generation of ultrasonic waves, often piezoactors are used that excite the grinding tools with vibrations of 20 kHz and amplitudes of a few microns (Markov 1966; Kuttruff 1988). Using an ultrasonic wave, the tool geometry is strongly restricted to guarantee the hybrid functionality (Siegert 2002; Dawe Instruments Ltd. 1967; Derks 1984). The paper describes a new way to calculate the design of tools suitable for their use in ultrasonic-assisted grinding. As a machining process, the manufacturing of spherical optics with cup-grinding wheels is selected.     

Arsonoliposome interaction with thiols: effect of pegylation and arsonolipid content of arsonoliposomes on their integrity during incubation in glutathione

Increased toxicity of arsonoliposomes towards cancer cells may be attributed to interaction between arsonolipids and cellular thiols which, would result in reduction of As(V) to the more toxic As(Ill). Cancer cells with high thiol contents may thus be more sensitive to arsonoliposomes, providing that the arsonolipid molecules that are incorporated in the liposome membrane can interact with thiol-containing compounds. For examination of this possibility we investigate the effect of incubating various compositions of arsonoliposomes with glutathione, on their integrity. If glutathione does interact with the As(V) of the arsonolipid headgroup, this should result in an alteration of the arsonoliposome membrane stability. We followed arsonoliposome integrity by measuring the release of vesicle-encapsulated calcein from arsonoliposomes with different lipid compositions, during incubation in glutathione. The results of this study show that the effect of glutathione on arsonoliposome integrity is higher (arsonoliposomes are less stable) when the arsonolipid content of their membranes increases. This indicates that arsonolipid molecules interact with glutathione, and in some cases, depending on the rigidity of their membranes; this interaction leads to a (higher or lower) destabilization of arsonoliposomes. The destabilizing effect of glutathione was higher for arsonoliposomes that were previously found to be less stable during incubation in serum proteins or, in other words, have lower membrane rigidity. In the case of pegylated-arsonoliposomes membrane destabilization was minimal and this may be related to the high stability demonstrated previously for these specific arsonoliposomes, or, it may indicate that pegylation results in prevention (total or partial) of arsonolipid-As interaction with thiols (perhaps because of steric repulsion).     

Quantum rod-sensitized solar cell: nanocrystal shape effect on the photovoltaic properties

The effect of the shape of nanocrystal sensitizers in photoelectrochemical cells is reported. CdSe quantum rods of different dimensions were effectively deposited rapidly by electrophoresis onto mesoporous TiO(2) electrodes and compared with quantum dots. Photovoltaic efficiency values of up to 2.7% were measured for the QRSSC, notably high values for TiO(2) solar cells with ex situ synthesized nanoparticle sensitizers. The quantum rod-based solar cells exhibit a red shift of the electron injection onset and charge recombination is significantly suppressed compared to dot sensitizers. The improved photoelectrochemical characteristics of the quantum rods over the dots as sensitizers is assigned to the elongated shape, allowing the build-up of a dipole moment along the rod that leads to a downward shift of the TiO(2) energy bands relative to the quantum rods, leading to improved charge injection.     

Physicochemical properties and structure of starches from Chinese rice cultivars

Starches from 10 different non-waxy rice cultivars in China were isolated and investigated for their physicochemical properties including the swelling power, solubility, syneresis, thermal, rheological and textural properties, and structure. The range of amylose content in 10 rice starches was between 18.1 and 31.6%. The branch chain length distribution of amylopectin revealed that the proportions of short (DP6–11), medium (DP12–17), and longer chains (DP18–23) were 4.6–11.1%, 47.0–51.6% and 25.3–31.8%, respectively. The relationships between different properties of rice starches were determined using Pearson correlation analysis. Amylose content was negatively correlated to swelling power (r = ?0.632, p ≤ 0.05) and positively correlated to gel hardness (r = 0.776, p ≤ 0.01). The percentage of short chains (DP6–11) was negatively related to the transition temperatures (T_o, T_p and T_c), T_oG′ and T_G′max, while the percentage of medium chains (DP12–23) was positively related. Various branch chain length amylopectins played different roles in rheological behavior of starch dispersions. The percentage of short chains (DP6–11) was positively correlated to G′ and G″(r = 0.832 and r = 0.775, respectively, p ≤ 0.01), and negatively correlated to tanδ peak (r = ?0.717, p ≤ 0.05). However, the percentage of longer chains (DP18–23) showed a negative relation with G′ and G″ (r = ?0.794, p ≤ 0.01; r = ?0.741, p ≤ 0.05), and a positive relation with tanδ peak (r = 0.668, p ≤ 0.05).     

Nanoparticle-Based Strain Gauges: Anisotropic Response Characteristics,Multidirectional Strain Sensing,and Novel Approaches to Healthcare Applications

Directional strain sensing is essential for advanced sensor applications in the field of human-machine interfaces and healthcare. Here, the angle dependent anisotropic strain sensitivity caused by charge carriers percolating through cross-linked gold nanoparticle (GNP) networks is studied and these versatile materials are used for the fabrication of wearable triaxial pulse and gesture sensors. More specifically, the anisotropic response of 1,9-nonanedithiol cross-linked GNP films is separated into geometric and piezoresistive contributions by fitting the measured data with an analytic model. Hereby, piezoresistive coefficients of g₁₁ ∼ 32 and g₁₂ ∼ 21 are extracted, indicating a slightly anisotropic response behavior of the GNP-based material. To use the material for healthcare applications, arrangements of three GNP transducers are patterned lithographically and fully embedded into a highly flexible silicone polymer (Dragon Skin 30). The new encapsulation method ensures good and robust electrical contacts and enables facile handling and protection from external influences. A facile read-out with wireless data transmission using off-the-shelf electrical components underlines the great potential of these devices for applications as skin-wearable healthcare sensors.     

Engineered Human Induced Pluripotent Cells Enable Genetic Code Expansion in Brain Organoids

Human induced pluripotent stem cell (hiPSC) technology has revolutionized studies on human biology. A wide range of cell types and tissue models can be derived from hiPSCs to study complex human diseases. Here, we use PiggyBac-mediated transgenesis to engineer hiPSCs with an expanded genetic code. We demonstrate that genomic integration of expression cassettes for a pyrrolysyl-tRNA synthetase (PylRS), pyrrolysyl-tRNA (PylT) and the target protein of interest enables site-specific incorporation of a non-canonical amino acid (ncAA) in response to an amber stop codon. Neural stem cells, neurons and brain organoids derived from the engineered hiPSCs continue to express the amber suppression machinery and produce ncAA-bearing reporter. The incorporated ncAA can serve as a minimal bioorthogonal handle for further modifications by labeling with fluorescent dyes. Site-directed ncAA mutagenesis will open a wide range of applications to probe and manipulate proteins in brain organoids and other hiPSC-derived cell types and complex tissue models.