Microencapsulation of bioactive compounds from mulberry (Morus alba L.) leaf extracts by protein–polysaccharide interactions

Mulberry leaf extracts were generated using four concentrations of ethanol (50%, 60%, 70%, and 95% v/v). A 60% ethanolic mulberry leaf extract (60E) yielded a high total phenolic content (TPC) and antioxidant activity using 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging and a ferric reducing antioxidant power (FRAP) assay. Coating materials were derived using a combination of soy protein isolates (SPI) and low methoxyl (LM) pectin in a 1:1 ratio. The effect of various parameters on microencapsulation, such as pH (3.5, 4.0, and 4.5) and the concentration of coating materials (2.5, 5.0 and 7.5% w/v), was studied. Microcapsules produced using 60E as a core material at pH 4.0 with 7.5% of coating material showed a high encapsulation yield, encapsulation efficiency, TPC and antioxidant activity.     

Stabilizing effect of the cyclodextrins additive to spray-dried particles of curcumin/polyvinylpyrrolidone on the supersaturated state of curcumin

Although curcumin is considered to have various therapeutic effects, its use as a functional food or supplement is restricted owing to its low water solubility and bioavailability. To increase the solubility of curcumin in water, the use of polyvinylpyrrolidone (PVP) and vinylpyrrolidone-vinyl acetate copolymers with a pyrrolidone skeleton was noted to be promising. In particular, the bi-component formulations of curcumin/PVP prepared through spray drying exhibited an amorphous state in powder X-ray diffraction observations and temporally increased the apparent solubility of curcumin to over 5000 times that of untreated curcumin; nevertheless, after 24 h, the solubility decreased owing to the unstable supersaturated state of curcumin. The addition of α-cyclodextrin (α-CyD) in the bi-component curcumin/PVP formulation helped maintain the supersaturated state of curcumin, whereas the addition of β- and γ-CyD led to the collapse of the supersaturated state. The addition of α-CyD can likely help inhibit the nucleation and crystal growth of curcumin, through the interaction among the solubilized units of curcumin/PVP and α-CyD.     

Determination of atomistic deformation of tricalcium silicate paste with high-volume fly ash

We examined the effect of incorporating high-volume fly ash on the atomic arrangement and interatomic deformation behavior of calcium silicate hydrates in tricalcium silicate paste upon exposure to external forces. The interatomic structural changes and strains under compressive load were assessed using synchrotron in situ high-energy X-ray scattering-based atomic pair distribution function analysis. Three different types of strains, which were (a) macroscopic strains from gauges on the surfaces of specimen, (b) strains in a reciprocal space (Bragg peak shift), and (c) strains in real space (PDF peak shift), were compared to each other. All monitored and calculated strains for tricalcium silicate-fly ash (50 wt% fly ash) paste were compared with the counterparts of the pure tricalcium silicate paste. Pair distribution function analysis in the range of r < 10 Å indicated that the atomic arrangement of tricalcium silicate-fly ash was similar to that of synthetic calcium silicate hydrates followed by that of pure tricalcium silicate paste. Moreover, the pair distribution function refinement results revealed that the calcium silicate hydrate structure in tricalcium silicate-fly ash paste was similar to tobermorite 11 Å, unlike that in pure tricalcium silicate paste. The interatomic strain of tricalcium silicate-fly ash in the real space (r < 20 Å) was smaller than that of tricalcium silicate under compression, which suggested that the incompressibility of calcium silicate hydrates at atomistic scale was enhanced by the incorporation of fly ash into it. This was likely to be caused by the increased silicate polymerization of calcium silicate hydrates, which was attributed to the increase in the amount of silicate in their structure via the addition of fly ash.     

Evaluation of Two Sets of Sorghum Bagasse Samples as the Feedstock for Fermentable Sugar Recovery via the Calcium Capturing by Carbonation (CaCCO) Process

Abstract: Sorghum bagasse samples from two sets (n6 and bmr6; n18 and bmr18) of wild-type and corresponding “brown midrib” (bmr) mutant strains of sweet sorghum were evaluated as the feedstock for fermentable sugar recovery via the calcium capturing by carbonation (CaCCO) process, which involves Ca(OH)₂ pretreatment of bagasse with subsequent neutralization with CO₂ for enzymatic saccharification. Saccharification tests under various pretreatment conditions of the CaCCO process at different Ca(OH)₂ concentrations, temperatures or residence periods indicated that bmr strains are more sensitive to the pretreatment than their counterparts are. It is expected that variant bmr6 is more suitable for glucose recovery than its wild-type counterpart because of the higher glucan content and better glucose recovery with less severe pretreatment. Meanwhile, bmr18showed higher scores of glucose recovery than its counterpart did, only at low pretreatment severity, and did not yield higher sugar recovery under the more severe conditions. The trend was similar to that of xylose recovery data from the two bmr strains. The advantages of bmr strains were also proven by means of simultaneous saccharification and fermentation of CaCCO-pretreated bagasse samples by pentose-fermenting yeast strain Candida shehatae Cs 4R. The amounts needed for production of 1 L of ethanol from n6, bmr6, n18, and bmr18samples were estimated as 4.11, 3.46, 4.03, and 3.95 kg, respectively. The bmr strains seem to have excellent compatibility with the CaCCO process for ethanol production, and it is expected that integrated research from the feedstock to bioprocess may result in breakthroughs for commercialization.     

Sweeteners interacting with the transmembrane domain of the human sweet-taste receptor induce sweet-taste synergisms in binary mixtures

Sweet enhancing effect of neohesperidin dihydrochalcone (NHDC) or cyclamate has been reported to be synergistic in human sensory tests. However, little is known about whether these synergisms are caused by the mechanism mediated by the human sweet-taste receptor. Here, we examined the sweetness intensity of sweet tastant mixtures by measuring the responses of cultured cells stably expressing the human sweet-taste receptor. The results showed that the cell response to sucrose was synergistically potentiated by the addition of NHDC or cyclamate. Moreover, a point mutation in the transmembrane domain of hT1R3 almost completely eliminated the enhancing effects of NHDC and cyclamate. These results suggest that ligand–receptor interactions in the transmembrane domain of hT1R3 are necessary for NHDC and cyclamate to elicit the synergistic potentiation of the receptor activation. Our results may provide the foundation of a molecular basis for receptor-based synergisms of sweet tastes in mixtures of diverse sweet substances.     

An intermittent control model of flexible human gait using a stable manifold of saddle-type unstable limit cycle dynamics

Stability of human gait is the ability to maintain upright posture during walking against external perturbations. It is a complex process determined by a number of cross-related factors, including gait trajectory, joint impedance and neural control strategies. Here, we consider a control strategy that can achieve stable steady-state periodic gait while maintaining joint flexibility with the lowest possible joint impedance. To this end, we carried out a simulation study of a heel-toe footed biped model with hip, knee and ankle joints and a heavy head-arms-trunk element, working in the sagittal plane. For simplicity, the model assumes a periodic desired joint angle trajectory and joint torques generated by a set of feed-forward and proportional-derivative feedback controllers, whereby the joint impedance is parametrized by the feedback gains. We could show that a desired steady-state gait accompanied by the desired joint angle trajectory can be established as a stable limit cycle (LC) for the feedback controller with an appropriate set of large feedback gains. Moreover, as the feedback gains are decreased for lowering the joint stiffness, stability of the LC is lost only in a few dimensions, while leaving the remaining large number of dimensions quite stable: this means that the LC becomes saddle-type, with a low-dimensional unstable manifold and a high-dimensional stable manifold. Remarkably, the unstable manifold remains of low dimensionality even when the feedback gains are decreased far below the instability point. We then developed an intermittent neural feedback controller that is activated only for short periods of time at an optimal phase of each gait stride. We characterized the robustness of this design by showing that it can better stabilize the unstable LC with small feedback gains, leading to a flexible gait, and in particular we demonstrated that such an intermittent controller performs better if it drives the state point to the stable manifold, rather than directly to the LC. The proposed intermittent control strategy might have a high affinity for the inverted pendulum analogy of biped gait, providing a dynamic view of how the step-to-step transition from one pendular stance to the next can be achieved stably in a robust manner by a well-timed neural intervention that exploits the stable modes embedded in the unstable dynamics.     

Investigation of Precipitation Behavior in Age-Hardenable Cu-Ti Alloys by an Extraction-Based Approach

We investigated the precipitation processes in Cu-4 mol pct Ti alloy specimens aged at 723 K (450 °C), by means of X-ray diffraction and chemical analyses of the precipitates extracted from the parent alloy specimens. Aging-induced precipitate particles of a spinodally decomposed disorder, α′; those of a metastable order, β′-Cu₄Ti; and those of a stable order, β-Cu₄Ti, were continuously formed in the aged specimens. The extraction of the precipitate particles from the aged specimens by submergence in a nitric solution allowed for not only the structural analyses of the constituent precipitate phases but also the quantitative evaluation of their chemical compositions and volume fractions. Early during the aging process, the supersaturated Cu solid solution decomposes spinodally in a continuous manner, and an unstable disorder, α′, appears. Then, fine needle-shaped β′-Cu₄Ti particles, which have a Ti content of approximately 37.5 mol pct, form in the Cu matrix. During prolonged aging, coarse cellular components composed of the terminal Cu solid solution and stable β-Cu₄Ti particles which have a Ti content of 20.5 mol pct nucleate and grow, primarily in the grain boundaries, at the expense of the metastable β′-Cu₄Ti particles. The volume fraction of the β′-Cu₄Ti particles in the alloy reaches a maximum of approximately 1.7 pct after aging for 24 hours, while that of the β-Cu₄Ti particles increases steadily to more than 18 pct after 480 hours. The volume fraction of the fine β′-Cu₄Ti particles in the alloy specimens remained constant throughout the age-hardening, indicating that the hardening is primarily owing to the fine dispersion of the β′-Cu₄Ti particles and not because of the large volume fraction of coarse β-Cu₄Ti particles.