Flavor Profile Analysis of Instant and Traditional Lanzhou Beef Bouillons Using HS-SPME-GC/MS, Electronic Nose and Electronic Tongue.

The volatile profiles and taste properties of Lanzhou beef bouillons prepared with traditional (A1−A8) and modern (B1, B2) processing methods were evaluated. A total of 133 volatiles were identified: olefins, aldehydes and alcohols from spices in traditional bouillons were significantly higher (p < 0.05) than those in instant bouillons. The characteristic volatile substances in traditional beef bouillons were eucalyptol, linalool, 2-decanone, ß-caryophyllene and geraniol; instant bouillons lacked 2-decanone and ß-caryophyllene, and the contents of the other three substances were low. PCA (principal component analysis) and CA (clustering analysis) showed that the instant bouillons have a similar volatile profile to traditional bouillons, and the results of E-nose and sensory evaluation also supported this conclusion. The E-tongue showed that the taste profiles of instant bouillons were significantly different from those of traditional bouillons, mainly due to lack of umami; however, sensory evaluation revealed that taste differences were not perceptible.

Extraction Optimization of Astragaloside IV by Response Surface Methodology and Evaluation of Its Stability during Sterilization and Storage.

Radix Astragali is referred to as a variety of food-medicine herb, and it is commonly applied as Traditional Chinese Medicine (TCM). However, it is extremely difficult to extract its bio-active compounds (astragaloside IV) and apply it in food processing efficiently, which restricts its practical applications. In this study, the conditions required for the extraction of astragaloside IV were optimized by following the response surface methodology. More specifically, ammonia with a concentration of 24% was used as an extracting solvent, the solid-liquid ratio was 1:10 (w:v); the Radix Astragali was soaked at 25 °C for 120 min in advance and then stirred at 25 °C for 52 min (150 rpm) to extract astragaloside IV. This method promoted the transformation of other astragalosides into astragaloside IV and replaced the traditional approach for extraction, the solvent reflux extraction method. The yield of astragaloside IV reached the range of 2.621 ± 0.019 mg/g. In addition, the stability of astragaloside IV was evaluated by detecting its retention rate during sterilization and 60-day storage. As suggested by the results, the astragaloside IV in acidic, low-acidic, and neutral solutions was maintained above 90% after sterilization (95 °C and 60 min) but below 60% in an alkaline solution. High temperature and short-term sterilization approach is more appropriate for astragaloside IV in an alkaline solution. It was also found out that the astragaloside IV obtained using our method was maintained over 90% when stored at room temperature (25 °C), and there was no significant difference observed to low temperature (4 °C) in solutions regardless of acidity.

An Energy Balance Clustering Routing Protocol for Intra-Body Wireless Nanosensor Networks.

Wireless NanoSensor Networks (WNSNs) are a new type of network that combines nanotechnology and sensor networks. Because WNSNs have great application prospects in intra-body health monitoring, biomedicine and damage detection, intra-body Wireless NanoSensor Networks (iWNSNs) have become a new research hotspot. An energy balance clustering routing protocol (EBCR) is proposed for the intra-body nanosensor nodes with low computing and processing capabilities, short communication range and limited energy storage. The protocol reduces the communication load of nano-nodes by adopting a new hierarchical clustering method. The nano-nodes in the cluster can transmit data directly to the cluster head nodes by one-hop, and the cluster head nodes can transmit data to the nano control node by multi-hop routing among themselves. Furthermore, there is a tradeoff between distance and channel capacity when choosing the next hop node in order to reduce energy consumption while ensuring successful data packet transmission. The simulation results show that the protocol has great advantages in balancing energy consumption, prolonging network lifetime and ensuring data packet transmission success rate. It can be seen that EBCR protocol can be used as an effective routing scheme for iWNSNs.

Flow induced stability of pluronic hydrogels: Injectable and unencapsulated nucleus pulposus replacement.

Poloxamers, or pluronics, have been proposed as biomimetic substitutes for physiological gels. Concern regarding their ability to resist swelling under fluid flows has impeded their implementation. Using a combination of techniques including cryo-TEM and rapid X-ray imaging, we found that rapid flow rates stabilized the gels against dissolution. Energy balance calculations confirmed that disentanglement of individual micelles was not possible at time scales faster than the reptation time when the system response was that of a solid which dissipated the hydrodynamic force field via cooperative deformation. In-vivo tests were performed where the hydrogel was injected as a substitute for the nucleus pulposus following discectomy in dogs. The results indicated that the gel was still present after 3 months, and radiographs indicated that compression of the disc space was prevented despite the gel being exposed to constant perfusion. STATEMENT OF SIGNIFICANCE: This paper demonstrates a highly unexpected result and counter intuitive result, namely the inverse dependence of the dissociation rate of a physical hydrogel on the flow velocity of the liquid medium. Using cryo-electron microscopy we demonstrate that the gel responds like deformable solid in high flow rates, with minimal dissociation. Since these gels are thermoreversible, they were injected into dogs, where we show that they were a viable alternative to the nucleus pulposus, without dissolution in physiological fluid flows for at least three months.

Modeling Gas Flow Dynamics in Metal-Organic Frameworks.

Modeling fluid flow dynamics in metal organic frameworks (MOFs) is a required step toward understanding mechanisms of their activity as novel catalysts, sensors, and filtration materials. We adapted a lattice Boltzmann model, previously used for studying flow dynamics in meso- and microporous media, to the nanoscale dimensions of the MOF pores. Using this model, rapid screening of permeability of a large number of MOF structures, in different crystallographic directions, is possible. The method was illustrated here on the example of an anisotropic MOF, for which we calculated permeability values in different flow directions. This method can be generalized to a large class of MOFs and used to design MOFs with the desired gas flow permeabilities.

Interface-engineered bistable [2]rotaxane-graphene hybrids with logic capabilities.

The use of high-quality graphene as a local probe in combination with photo excitation helps to establish a deep mechanistic understanding of charge generation/quenching processes under lying the graphene/environment interface. By combining a non-destructive bottom-up assembly technique with sensitive graphene-based transistors, a bistable [2]rotaxane-graphene hybrid device, which exhibits a symmetric mirror-image photoswitching effect with logic capabilities, is produced.

Direct optical characterization of graphene growth and domains on growth substrates.

We detailed a facile detection technique to optically characterize graphene growth and domains directly on growth substrates through a simple thermal annealing process. It was found that thermal annealing transformed the naked Cu to Cu oxides while keeping graphene and graphene-covered Cu intact. This increases the interference color contrast between Cu oxides and Cu, thus making graphene easily visible under an optical microscope. By using this simple method, we studied the factors that affect graphene nucleation and growth and achieved graphene domains with the domain size as large as ~100 µm. The concept of chemically making graphene visible is universal, as demonstrated by the fact that a solution process based on selective H(2)O(2) oxidation has been developed to achieve the similar results in a shorter time. These techniques should be valuable for studies towards elucidating the parameters that control the grains, boundaries, structures and properties of graphene.