RESUMEN
This study aimed to investigate the physicochemical properties of modified starch prepared through the simultaneous heat-moisture and phosphorylation treatment (HMPT) and osmotic pressure treatment (OPT) for water caltrop starch (WCS), mung bean starch (MBS), and amylose-rich corn starch (CS) for different time periods. Furthermore, variations in starch content [amylose and resistant starch (RS)], swelling powder (SP), water solubility index (WSI), crystallinity, thermal properties, gelatinization enthalpy (ΔH), and glycemic index (GI) were examined. This study demonstrates that neither HMPT nor OPT resulted in a significant increase in the resistant starch (RS) content, whereas all samples succeeded in heat-treating at 105⯰C for another 10â¯min exhibited a significant increase in RS content compared to their native counterparts. Moreover, the gelatinization temperatures of the three starches increased (To, Tp, and Tc), whereas their gelatinization enthalpy (ΔH) and pasting viscosity decreased. In particular, the GI of all three modified starches subjected to HMPT or OPT showed a decreasing trend with modification time, with OPT exhibiting the best effect. Therefore, appropriate modification through HMPT or OPT is a viable approach to develop MBS, WCS, and CS as processed foods with low GI requirements, which exceptionally may be suitable for canned foods, noodles, and bakery products.
Asunto(s)
Calor , Presión Osmótica , Solubilidad , Almidón , Vigna , Agua , Zea mays , Zea mays/química , Almidón/química , Agua/química , Vigna/química , Fosforilación , Fenómenos Químicos , Amilosa/química , Amilosa/análisis , Viscosidad , Termodinámica , LythraceaeRESUMEN
In this study, we enhanced the toughness of epoxy resin by blending it with the diblock copolymer poly(ethylene oxideâ»bâ»Îµ-caprolactone) (PEO-b-PCL) with a benzoxazine monomer (PA-OH) as the thermal curing agent. After thermal curing, Fourier transform infrared spectroscopy revealed that intermolecular hydrogen bonding existed between the OH units of the epoxyâ»benzoxazine copolymer and the Câ»Oâ»C (C=O) units of the PEO (PCL) segment. Differential scanning calorimetry and dynamic mechanical analysis revealed that the glass transition temperature and storage modulus of the epoxyâ»benzoxazine matrix decreased significantly upon increasing the concentration of PEO-b-PCL. The Kwei equation predicted a positive value of q, consistent with intermolecular hydrogen bonding in this epoxyâ»benzoxazine/PEO-b-PCL blend system. Scanning electron microscopy revealed a wormlike structure with a high aspect ratio for PEO-b-PCL as the dispersed phase in the epoxyâ»benzoxazine matrix; this structure was responsible for the improved toughness.
RESUMEN
Sleep onset is associated with marked changes in behavioral, physiological, and subjective phenomena. In daily life though subjective experience is the main criterion in terms of which we identify it. But very few studies have focused on these experiences. This study seeks to identify the subjective variables that reflect sleep onset. Twenty young subjects took an afternoon nap in the laboratory while polysomnographic recordings were made. They were awakened four times in order to assess subjective experiences that correlate with the (1) appearance of slow eye movement, (2) initiation of stage 1 sleep, (3) initiation of stage 2 sleep, and (4) 5 min after the start of stage 2 sleep. A logistic regression identified control over and logic of thought as the two variables that predict the perception of having fallen asleep. For sleep perception, these two variables accurately classified 91.7% of the cases; for the waking state, 84.1%.