Effect of Single and Dual Hydrothermal Treatments on the Resistant Starch Content and Physicochemical Properties of Lotus Rhizome Starches

Heat-moisture treatment (HMT) changed the morphology and the degree of molecular ordering in lotus rhizome (Nelumbo nucifera Gaertn.) starch granules slightly, leading to some detectable cavities or holes near hilum, weaker birefringence and granule agglomeration, accompanied with modified XRD pattern from C- to A-type starch and lower relative crystallinity, particularly for high moisture HMT modification. In contrast, annealing (ANN) showed less impact on granule morphology, XRD pattern and relative crystallinity. All hydrothermal treatment decreased the resistant starch (from about 27.7–35.4% to 2.7–20%), increased the damage starch (from about 0.5–1.6% to 2.4–23.6%) and modified the functional and pasting properties of lotus rhizome starch pronouncedly. An increase in gelatinization temperature but a decrease in transition enthalpy occurred after hydrothermal modification, particularly for hydrothermal modification involved with HMT. HMT-modified starch also showed higher pasting temperature, less pronounced peak viscosity, leading to less significant thixotropic behavior and retrogradation during pasting-gelation process. However, single ANN treatment imparts a higher tendency of retrogradation as compared to native starch. For dual hydrothermally modified samples, the functional properties generally resembled to the behavior of single HMT-modified samples, indicating the pre- or post-ANN modification had less impact on the properties HMT modified lotus rhizome starch.

A novel composite cotton yarn with phase change and electrical conductivity functions

PAN/PEG/CNT/cotton composite yarn (PPCCY) was fabricated by impregnating PEG2000–10000 into CNT/cotton yarn (CCY) and coating electrospun PAN around its surface. The effects of PEG type on the morphology, structure, electrical resistance and phase change behavior of the produced composite yarns were studied thoroughly by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric(TG), electrical resistance tester and infrared thermal images. The experimental results indicated that the resulting compound yarn consisted of conductive yarn within which the spacing between cotton fibers was fulfilled by PEG, rendering phase transition enthalpy from 126–150 Jg−1. The composite yarn exhibited adjustable temperature and thermal storage and electrical conductivity abilities. The composite yarn demonstrated good responsive properties to external electrical and thermal stimuli and had reversible heat conversion and storage, which shows a promise for applications in electrical wearable fabrics.

Phase change materials and their use for energy accumulation

Problems with overheating and unstable temperature of industrial equipment are the reasons for generating significant costs that for companies. Solving the problems related to heat removal is a challenge in modern industry. Phase change materials are the solution to these challenges (PCM). These substances can accumulate and release large amounts of thermal energy during the phase change transition. The value of the phase transition enthalpy determines the energy storage capacity. The paper presents the results of phase transitions of selected materials. The measurements were carried out on a stand for testing phase change materials. The laboratory stand made it possible to determine the thermodynamic parameters of the phase transition. The substances analysed are kinds of paraffin of different chemical composition. Due to the diversity of substances, it is possible to analyse the influence of the chemical composition on possible uses in industrial applications for energy storage.

A calculation model for the heat capacity of beef with different moisture during freezing taking into account free water crystallization

The paper proposes a model for the process of free moisture crystallization in beef within the framework of the Debye concept with establishment of dependencies of model parameters on the initial moisture content. Model adequacy was validated by comparison of the calculation results with the results of the experiments on determination of values of heat capacity and phase transition enthalpy in beef with different initial moisture obtained by the differential scanning calorimetry method. It is shown that the end of free water phase transition in beef with initial moisture in a range of 37% to 80% occurs at a temperature of 243 К. Calculation dependencies of parameters of the model used for calculation of beef heat capacity are presented.

Dirhamnolipid ester – formation of reverse wormlike micelles in a binary (primerless) system

We report new dirhamnolipid ester forming reverse wormlike micelles in nonpolar solvents without the addition of any primer. Therefore, these compounds represent a rare case of a binary system showing this gel-like behavior. In this study, the influence of the concentration of the rhamnolipid ester and the ester alkyl chain length on the rheological properties of the reverse wormlike micelles in toluene was investigated in detail. Highly viscoelastic solutions were obtained even at a relatively low concentration of less than 1 wt %. The phase transition temperatures indicate that the formation of reverse wormlike micelles is favored for dirhamnolipid esters with shorter alkyl chain lengths. Oscillatory shear measurements for the viscoelastic samples reveal that the storage modulus (G') and the loss modulus (G'') cross each other and fit the Maxwell model very well in the low-ω region. As is typical for wormlike micelle systems, the normalized Cole–Cole plot of G''/G'' max against G'/G'' max was obtained as a semicircle centered at G'/G'' max = 1. The formation of network structures was also verified by polarized light microscopy. The sample was birefringent at ambient temperature and anisotropic at an elevated temperature. Differential scanning calorimetry analysis yielded a transition enthalpy of about ΔH SG/GS = ±7.2 kJ/mol. This value corresponds to a strong dispersion energy and explains the formation of the highly viscous gels by the entanglement of wormlike micelles through the interaction of the alkyl chains.

Application of a Clapeyron-Type Equation to the Volume Phase Transition of Polymer Gels

The applicability of the Clapeyron equation to the volume phase transition of cylindrical poly(N-isopropylacrylamide)-based gels under external force is reviewed. Firstly, the equilibrium conditions for the gels under tension are shown, and then we demonstrate that the Clapeyron equation can be applied to the volume phase transition of polymer gels to give the transition entropy or the transition enthalpy. The transition enthalpy at the volume phase transition obtained from the Clapeyron equation is compared with that from the calorimetry. A coefficient of performance, or work efficiency, for a gel actuator driven by the volume phase transition is also defined. How the work efficiency depends on applied force is shown based on a simple mechanical model. It is also shown that the force dependence of transition temperature is closely related to the efficiency curve. Experimental results are compared with the theoretical prediction.

‐sitosterol and gentisic acid loaded 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine liposomal particles

The aim of the present study was the examination of the impact of -sitosterol andgentisic acid on the characteristics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine(DPPC) liposomal particles: (a) bilayer permeability (fluorescence spectroscopy),(b) particle size, polydispersity index (PDI) and zeta potential (photon correlationspectroscopy) and (c) thermal properties (differential scanning calorimetry). -sitosterol induced the increase of liposomal bilayer rigidity, due to rearranging ofthe phospholipid chains, while gentisic acid enhanced the membrane fluidity, dueto the reduced orderliness and the increase of phospholipid dynamics. The inclusionof -sitosterol in liposomes caused a significant increase in particle diameterand PDI, while the encapsulation of gentisic acid did not have influence on particlesize distribution. Apart from that, the presence of -sitosterol resulted in thesignificant zeta potential increase, and thus a better stability of liposomal spheres(in the absence and in the presence of gentisic acid). -sitosterol decreased maintransition temperature (Tm) and phase transition enthalpy (H), and caused thedisappearance of the pre-transition peak as well, whereas the presence of gentisicacid produced a slight decrease in Tm and increase of H. Therefore, gentisic acidhad more favourable, stabilizing interactions with phospholipids than -sitosterol.Thus, it can be concluded that -sitosterol is located in the bilayer interior betweenphospholipids acyl chains, and gentisic acid is incorporated near the outer leaflet ofthe phospholipid membrane, next to the polar head groups. -sitosterol and gentisicacid loaded DPPC liposomal particles have a potential to be used in food andpharmaceutical products, due to the important individual and possible synergisticbeneficial health properties of -sitosterol and gentisic acid.