Search

1,2-Diacetylbenzene (DAB) is a metabolite of 1,2-diethylbenzene, which is commonly used in the manufacture of plastics and gasoline. We examined the neurotoxic effects of DAB in young and old rats, particularly its effects on hippocampus. Previously, we reported DAB impairs hippocampal neurogenesis but that the underlying mechanism remained unclear. In this study, we evaluate the toxicities exhibited by DAB in the hippocampi of 6-month-old (young) and 20-month-old (old) male SD rats by treating animals intraperitoneally with DAB at 3 mg/kg/day for 1 week. Hippocampal areas were dissected from brains and RNA was extracted and subjected to RNA-seq analysis. RNA results showed animals exhibited age-dependent sensitivity to the neurotoxic effects of DAB. We observed that inflammatory pathways were up-regulated in old rats but that metabolism- and detoxification-related pathways were up-regulated in young rats. This result in old rats, especially upregulation of the TREM1 signaling pathway (an inflammatory response involved in Alzheimer's disease (AD)) was confirmed by RT-PCR. Our study results provide a better understanding of age-dependent responses to DAB and new insight into the association between DAB and AD.

This study was supported by the Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT, Korea (Grant number NRF-2016R1A2B4007452).

An isotropic pitch was electrospun in the form of a felt, by adopting a specially-designed dual concentric nozzle system. In the dual nozzle system, the solvent of tetrahydrofuran (THF) flowed independently through the outer nozzle, and relieved the problem of the too rapid coagulation of pitch fibers in the inner nozzle. Unlike the non-woven pitch fabric prepared by conventional electrospinning, the pitch felt had a characteristic morphology of fiber bundles, highly isolated from each other with few fusion points between fibers. The felt morphology was retained, during carbonization of the pitch felt. In consequence, the carbon felt took a sponge-like form, and showed extremely low bulk density of ca. 4.2×10−2 g/cm3, almost one tenth of that of the polyacrylonitrile-based carbon fibers in the form of non-woven fabric. The cross-section of the felt fibers exhibited the shape of a dog bone, due to asymmetric shrinkage of fibers during electrospinning. Physical properties of the felt were affected by pitch concentration, flow rate, and carbonization temperature.

The solution of poly(2-cyano-p-phenylene terephthalamide) (CY-PPTA) in N,N-dimethyl acetamide/lithium chloride exhibited a concentration-dependent transition of liquid crystalline textures from nematic-rich to cholesteric-rich with increasing concentration above the critical concentration. The 2D correlation analysis of the FTIR spectra revealed that the dipolar interactions between cyano groups of the polymer increased as concentration increased. The polarized cyano group withdrew the delocalized π-electrons in the C-N bond of the amide group of the polymer, increasing its single bond character. The molecular simulation based on this spectroscopic evidence proposed a change of molecular shapes of CY-PPTA from linear rigid rod to semi-rigid helix. The semi-rigid helical conformation where the single bond character was prevalent over the delocalized one in the C-N bond would develop a cholesteric liquid crystalline texture.

Poly(1-oxotrimethylene) (POTM) was dissolved in aqueous solutions containing ZnCl2, CaCl2, and LiCl, and the effects of boric acid introduction on the phase stability of the POTM solutions over various aging times were investigated. In the absence of boric acid, aging at 70°C for 8 h notably reduced the loss tangent (tanδ) for the 7.0 wt.% POTM solutions. Addition of boric acid into unaged solutions had little effect on tanδ over the frequency range measured, regardless of its content, whereas addition of 0.3-1.0 wt.% of boric acid into aged solutions increased tanδ. The dynamic viscosity of the POTM solutions with 1.0 wt.% boric acid was affected little by aging time. Conversely, the POTM solutions without boric acid exhibited increased dynamic viscosity in the low-frequency range with aging time. In addition, the slope of the solutions in the Cole-Cole plot decreased with increasing aging time in the absence of boric acid, whereas aging time had little effect in the presence of 1.0 wt.% boric acid. For dilute POTM solutions (i.e., 0.5 g/dL), the reduced viscosity decreased with increasing aging time in the absence of boric acid, while it was affected little in solutions with the addition of 1.0 wt.% boric acid. In the UV-Vis spectra, the aging-time-dependent increase of the absorbance peak at 390 nm was associated with the generation of a chromophoric complex in the POTM solutions. Conversely, the disappearance of the peak due to the addition of boric acid indicated suppression of complex formation.

Most inorganic nucleating agents for poly(ethylene terephthalate) (PET) have limited nucleating ability due to poor compatibility with PET. Polyhedral oligomeric silsesquioxanes (POSS) is a type of cage-shaped organic/inorganic hybrid nanoparticles with three different particle sizes: octameric (T8), decameric (T10), and dodecameric (T12). POSS is considered as a promising nucleating agent for PET because the inorganic moieties contribute to high thermal stability and nucleation and the organic moieties can be tethered to PET chains. In contrast to T8 POSS, the nucleation ability of T12 POSS for PET has been poorly reported. In this study, our newly synthesized aminopropyl functionalized T12 POSS (A-POSS) is proposed as a potential nucleating agent for PET. The amine group of A-POSS is able to be chemically conjugated to PET chains, thereby giving a more homogeneous dispersion of T12 POSS in PET than non-functional T12 Phenyl POSS (N-POSS). Its PET composites gave a ∼1.2 fold higher crystallization temperature and ∼2.7 fold higher shear-induced crystallization rate over pristine PET. Such nucleating effects for PET is more effective than those of non-functional T12 POSS and the more widely studied T8 POSS. This strategy is potentially beneficial for the high-shear melt processes of PET such as spinning and film extrusion.

The molecular modification of polycaprolactone (PCL) is of great importance for producing optimum physical properties for a given application. Linear polycaprolactone (L-PCL) and 4-arm star polycaprolactone (4-PCL) with similar molecular weights were prepared, and their rheological, thermal, and morphological properties were investigated in relation to their molecular architecture. In dilute solutions, L-PCL exhibited a higher intrinsic viscosity than 4-PCL. In the molten state, the former displayed a higher viscosity and greater temperature dependence of molecular relaxation time than the latter. DSC thermograms showed that molecular architecture had little effect on the melting/crystallization temperature and crystallinity. Thermogravimetric analysis indicated that the introduction of a branched structure deteriorated the thermal stability of PCL, which might be associated with the increased number of hydroxyl end groups in the polymer chains. In isothermal crystallization under shear at two different temperatures, 4-PCL exhibited longer crystallization times than L-PCL. A more notable difference in dynamic crystallization behavior caused by the chemical architecture was observed at 40°C than at 45°C. Examination with a wide angle X-ray diffractometer revealed that shear and temperature applied during isothermal crystallization, as well as chemical architecture, had little effect on the crystal structure.

The physical properties and gelation behavior of polyacrylonitrile (PAN) solutions were investigated in mixed solvents of N,N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). In the individual solubility parameters, DMSO had the polar term closer to PAN than DMF. The SAXS profiles and FT-IR spectra of 20 wt% PAN solutions confirmed that internal structure and intermolecular complex between nitrile groups were broken up by the DMSO molecules. The slope on Cole-Cole plot, a measure of the solution heterogeneity, was increased with the mole fraction of DMSO (XDMSO) via three distinct zones. The homogenization was particularly noticeable in Zone 1 (0.0 < XDMSO < 0.4) and Zone 3 (0.7 < XDMSO < 1.0). The Huggins constant and UV/vis absorbance at 268 nm of dilute solutions decreased sharply above the XDMSO of 0.7 in Zone 3. This indicated the marked increase of the PAN solubility by dissociating the intramolecular complex between nitrile groups. In Zone 1, the storage modulus of 20 wt% PAN solutions decreased but loss modulus remained almost constant with the XDMSO at the lower frequency below 1 rad/s, indicating the weakening of the true entanglement points possessing the intermolecular complexes. The mechanism represented that the intermolecular complexes between nitrile groups were dissociated by DMSO earlier than the intramolecular ones.

The dipole-dipole interactions between polar nitrile groups of polyacrylonitrile (PAN) affected the molecular weight distribution (MWD)-dependent viscosity behavior of the solutions in N,N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). In both solvents, the 16 wt% PAN solutions of broader MWD but same weight average molecular weight (MWw) of 150,000 showed more prominent shear-thinning behavior, agreeing qualitatively with the theoretical prediction by Middleman. The dependence of the thinning behavior on the MWD was more pronounced with DMSO. The decrease of the power-law index by broadening of the MWD was more noticeable in DMSO than in DMF. The UV/vis and FTIR spectra confirmed that DMF produced stronger intra- and intermolecular dipole-dipole pairs between nitrile groups of PAN than DMSO. This indicated that physical association between polymer molecules limited the internal plasticizing effect of the low MWw molecules by disturbing the chain interdiffusion and shear-induced disentanglement. Over the whole range of frequency measured, the higher content of the higher MWw molecules in the broader MWD solutions resulted in the increase of dynamic viscosity and relaxation time but decrease of loss tangent.

Effects of chain conformation of polyacrylonitrile (PAN) on the aging behavior of the solutions in N , N -dimethyl formamide (DMF) were investigated over the range of aging temperature from 30 to 100 °C. Aging of PAN solutions reduced the hydrodynamic diameter and inherent viscosity at 0.5 g/dl. The absorption peak at 268 nm in the UV–vis spectra represented the dipole-dipole pairs of the physically associated nitrile (CN) groups, whose intensity increased with aging temperature above 60 °C. The results confirmed that aging of the solutions produced the contracted chain conformation with predominantly anti-parallel orientation of CN groups. Analyses of the temperature-dependent FTIR spectra and its two-dimensional correlation spectroscopy evidenced that thermal-induced conformational change of PAN to the contracted structure directly induced the reorientation of CN groups and resultant dipole-dipole pairs in the 70–100 °C range. In addition, the aging caused the release of the bound DMF molecules from CN groups. In the 30–60 °C range, however, the conformational change to the extended structure was followed by the increase of solvent entropy and resultant dissociation of solvent aggregates. Then, highly diffused DMF molecules separated the partially dissociated CN groups.

The viscoelastic properties of polyacrylonitrile (PAN) gels prepared from the 20 wt% solutions in N,N-dimethyl formamide (DMF) were investigated under large amplitude oscillatory shear (LAOS) in terms of aging temperature of the solutions from 30 to 100 °C. Aging of PAN solutions reduced intrinsic viscosity and hydrodynamic diameter with little degradation. In the UV–vis spectra, the absorption peak at 268 nm represented the dipole-dipole pairs of physically associated nitrile groups, whose intensity increased with aging temperature. These results confirmed that aging of the solutions gave rise to the contracted chain conformation with anti-parallel orientation-dominant nitrile groups. In 20 wt%, aged solutions showed gelation behavior more rapid than fresh one during storage at 25 °C. At the imposed strain amplitude of 400% in the LAOS measurement, PAN gel prepared from fresh solution gave sinusoidal waveform signal of stress and ellipse-shape Lissajous curve. However, gels from the solutions aged above 60 °C showed non-sinusoidal stress waveform and characteristic Lissajous pattern, representing strain-stiffening behavior. In addition, the gel of the solution aged at 100 °C gave the greater strain-stiffening ratio than the initial value after the successive LAOS tests at 80 and 30 °C, indicating the thermo-irreversibility.

In this study, efforts were made to enhance the mechanical properties of the poly(vinyl alcohol) (PVA) fibers of medium molecular weight(number-average degree of polymerization=1735) varying the ratio in DMSO/H2O mixed solvent and spinning/drawing conditions. The gel fibers prepared from pure DMSO were opaquely frozen in the coagulating bath of -20℃. However, transparent gel fibers were formed without freezing for the mixture to contain water less than 80wt%. As the amount of water in the mixture increased the residual solvent in the coagulated gel fibers decreased ranging from 85 to 42wt%. The complex viscosity increased with increasing PVA concentration in 80/20 DMSO/H2O exhibiting remarkable shear thinning at 18wt%. In the Cole-Cole plot, the 18wt% PVA solutions gave a deviated curve from 12 and 15wt% ones. Thus the optimum PVA concentration for the spinning processing of medium MW PVA solutions in 80/20 DMSO/H2O was determined to 18wt% with rheological concept. Low degree of drawing during hot drawing process in the dry state was available for high bath draft in the coagulation bath. The most improved mechanical properties were observed by applying the highest possible draw ratio attained by reducing bath draft over multi-step drawing process. In the given bath draft, linear relationship was observed between both tensile strength and modulus and draw ratio showing the inflection points at the draw ratio of 19.5 and 18.0 for tensile strength and modulus, respectively.

The effects of temperature on the physical properties of the cellulose solutions in N,N-dimethylacetamide (DMAc) containing 9 (solvent-9) or 6 wt% (solvent-6) lithium chloride (LiCl) were investigated over the temperature range of 30 to 80 °C. The cellulose solution exhibited a lower critical solution temperature (LCST) behavior over the temperature range observed. The content of LiCl affected the thermoreversible LCST behavior of cellulose solutions, which was almost thermoreversible over the temperature range of 30 to 80 °C for solvent-9 and 30 to 50 °C for solvent-6. The partial thermoreversibility of cellulose chain between 60 and 80 °C in solvent-6 could be explained by increased intramolecular interactions between cellulose molecules with increasing temperature. The thermoreversible LCST behavior of cellulose solution for solvent-9 was further supported by dynamic light scattering measurement which also verified the larger decrease of cellulose chain dimensions in solvent-6 between 60 and 80 °C. The cellulose solutions in DMAc/LiCl exhibited little thermal degradation in the short-term aging between 30 and 80 °C. However, they produced a little thermal degradation in the long-term aging between 80 and 100 °C.

The respective roles of the aqueous solutions of zinc chloride (ZnCl2), calcium chloride (CaCl2), and lithium chloride (LiCl) in the dissolution process of poly(1-oxotrimethylene) (ECO) were investigated. The ECO was soluble only in the ZnCl2-based aqueous solutions. The ZnCl2 aqueous solutions dissolved ECO when the metal salt content exceeded 65 wt%, following a mechanism analogous to Lewis acid/base reaction. In the case of the aqueous solution of 70 wt% ZnCl2, the ECO solubility was limited to 6 wt% because of heterogeneity of the resultant solution. However, an addition of CaCl2 (10 wt%) or LiCl (10 wt%) to the ZnCl2 aqueous solution widened the soluble range of ECO up to 8 wt%. The Cole-Cole plot exhibited that CaCl2 improved homogeneity of the solution but LiCl reduced it. In addition, the addition of both LiCl and CaCl2 decreased the dynamic viscosity of the ECO solutions, which was more noticeable with LiCl.

The physical properties of dilute cellulose solutions in N,N-dimethyl acetamide (DMAc) including 9 wt% lithium chloride (LiCl) were investigated in terms of concentration, temperature and molecular weight of cellulose. Over the concentration range of 0.01 to 2.5 g/dL, the viscosity of the cellulose solutions exhibited a lower critical solution temperature (LCST) behavior which proved thermoreversible between 30 and 60 °C. The LCST behavior was further supported by dynamic light scattering measurement. In the extremely dilute concentration range, 0.01 to 0.08 g/dL, the reduced viscosity (η red ) of cellulose solutions was increased with decreasing concentration. The anomalous coil expansion with decreasing concentration could be explained by the increase of the conductivity of cellulose solutions with decreasing concentration, which was also verified by dynamic light scattering experiment. In the concentration range of 0.1 and 2.5 g/dL, both cellulose solutions gave a drastic increase of η red in the vicinity of the critical concentration (C*), 0.9 g/dL. The slope of the curve of η red vs. concentration was higher for the cellulose of higher molecular weight, but it did not change with temperature between 30 and 60 °C.

Dissolution behavior of polyacrylontrile (PAN) in N,N-dimethylformamide (DMF) and dimethylsulfoxide (DMSO) is investigated in terms of dipole-dipole interactions at polymer-solvent interface. Fourier-transformed infrared (FTIR) imaging of polymer-solvent interface under static dissolution condition at 25 °C and 60 °C exhibits the gel-like swollen layer in the early stage of dissolution for both solvents. This layer readily disappears in PAN-DMSO and DMSO molecules penetrate deep into the polymer phase, whereas that in PAN-DMF is still observed until 12 h even at 60 °C. The better dissolving ability of DMSO is interpreted by higher intrinsic viscosity and lower Huggins’ constant. The solubility (solution homogeneity) is also evaluated by rheological analysis in a wide concentration range of 8–20 wt%. At above 15 wt%, DMSO produces homogeneous solution at 60 °C even without stirring, showing the lower Newtonian flow region. On the other hand, it is necessary to apply vigorous stirring and heating for PAN-DMF system in order to prepare concentrated solution. DMSO provides greater slope of the Cole-Cole plot by rheological measurement than DMF, indicating better solution homogeneity in PAN-DMSO. The FTIR spectra and 2D correlation analysis show that both DMSO and DMF dissolve PAN in a way of sequential contributions of enthalpic and entropic factors. However, DMSO exhibits predominant contribution by enthalpic factor, suggesting that enthalpy change of mixing is a driving force of PAN dissolution in DMSO, whereas dissolution of PAN-DMF is governed by kinetic control.

Ethylene vinyl acetate (EVA) copolymers with two different VA contents (15 and 33 wt.%, denoted by EVA15 and EVA33, respectively) were melt compounded with multi-walled carbon nanotubes (MWNTs) and the effect of VA and nanotube contents on the rheological, thermal and morphological properties was investigated. The addition of nanotubes into both EVAs increased the onset temperature of crystallization and broadened the peak, but further addition from 3 wt.% slightly decreased the temperature with increasing nanotube contents. In the wide angle X-ray diffraction patterns the peak of EVA15 was little affected by the presence of nanotubes but that of EVA33 slightly shifted to higher degree and became sharper with increasing nanotube contents. Dynamic viscosity (η') increased with nanotube contents giving abrupt increase at 2 wt.% nanotubes. Loss tangent decreased with increasing nanotube contents exhibiting the plateau-like behavior over most of the frequency range from 2 wt.% nanotubes. In the Casson plot, yield stress increased with nanotube content and its increasing extent was more notable for more VA content. In the Cole-Cole plot, the presence of nanotubes from 2 wt.% gave rise to the deviation from the single master curve by decreasing the slope. The deviated extent of EVA33 became more remarkable with increasing nanotube contents than that of EVA15. The stress-strain curve showed that more improved tensile modulus and yield stress were achieved by the introduction of MWNTs for EVA 33 than for EVA15. Tensile strength of EVA33 increased with increasing nanotube contents, while that of EVA15 decreased.

The current study was designed to estimate the pork quality traits using metabolites from exsanguination blood and postmortem muscle simultaneously under the Korean standard pre- and post-slaughter conditions. A total of 111 Yorkshire (pure breed and castrated male) pigs were evaluated under the Korean standard conditions. Measurements were taken of the levels of blood glucose and lactate at exsanguination, and muscle glycogen and lactate content at 45 min and 24 h postmortem. Certain pork quality traits were also evaluated. Correlation analysis and multiple regression analysis including stepwise regression were performed. Exsanguination blood glucose and lactate levels were positively correlated with each other, negatively related to postmortem muscle glycogen content and positively associated with postmortem muscle lactate content. A rapid and extended postmortem glycolysis was associated with high levels of blood glucose and lactate, with high muscle lactate content, and with low muscle glycogen content during postmortem. In addition, these were also correlated with paler meat color and reduced water holding capacity. The results of multiple regression analyses also showed that metabolites in exsanguination blood and postmortem muscle explained variations in pork quality traits. Especially, levels of blood glucose and lactate and content of muscle glycogen at early postmortem were significantly associated with an elevated early glycolytic rate. Furthermore, muscle lactate content at 24 h postmortem alone accounted for a considerable portion of the variation in pork quality traits. Based on these results, the current study confirmed that the main factor influencing pork quality traits is the ultimate lactate content in muscle via postmortem glycolysis, and that levels of blood glucose and lactate at exsanguination and contents of muscle glycogen and lactate at postmortem can explain a large portion of the variation in pork quality even under the standard slaughter conditions.

The crystallization behavior of the ethylene, propylene and carbon monoxide/thermoplastic elastomer (EPCO/HY) blends in the static and dynamic states revealed that immiscible HY retarded the crystallization of EPCO without changing its crystal structure. The large difference in the elastic moduli of the two polymers at the crystallization temperature was the principal reason for the retardation process. The retardation of crystallization could be explained by steric hindrance or a shield effect of the HY phase on the growth of EPCO spherulites at a temperature near the crystallization temperature (T c).

A novel isotropic pitch composed of linear methylene chains of polycondensed aromatic molecules was synthesized from naphtha-cracked oil through bromination and subsequent dehydrobromination (NB). Isotropic pitch-based carbon fiber obtained from the prepared NB yielded an unprecedentedly high tensile strength and elongation at break of 1500 MPa and 3.2%, respectively, following carbonization at only 800 °C for 5 min. The aromatic components of NB were primarily condensed cyclic compounds containing three and four aromatic rings. In contrast, a pitch prepared by simple distillation (ND), was composed of compounds containing three to six aromatic rings, which carried the tensile strength of carbon fiber by only 700 MPa with the similar fiber diameter. Interestingly, TOF-Mass analysis indicated that the molecular weight of the NB was higher than that of the ND. 13 C-NMR analyses revealed that the NB pitch contained up to 18.8% aliphatic and naphthenic components compared to the 2.8% found in the ND pitch. Both isotropic pitches exhibited Bingham behavior above their softening temperatures. However, the linear chains of the NB pitch resulted in a higher degree of shear-thinning than was observed with the nonlinear ND pitch. This could result in a greater degree of molecular orientation during spinning.

The thermal decomposition behavior of the terpolymer of ethylene, propylene, and carbon monoxide (EPCO), stabilized by calcium hydroxyapatite (CHA) as an acid scavenger and 2,2′-oxamidobis-[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (OHP) as a radical scavenger, was investigated in terms of shear, temperature and stabilizer composition. The optimum composition of two stabilizers was affected by shear condition as well as thermal history. The thermal stability at the static state evaluated by DSC indicated that the simultaneous use of CHA and OHP produced a synergistic effect and the optimum composition of CHA/OHP ranged from 4/1 to 8/1 by wt at the total content of 0.5 wt%. However, dynamic rheological analysis revealed that shearing changed the optimum composition of the stabilizers to 7/1 by wt but had little effect on the total stabilizer content. In addition, the synergistic effect was not observed at the particular composition of 1/4 by wt. The increase of melt viscosity of EPCO with time ascertained that the thermal decomposition of EPCO accompanied crosslinking through the intermolecular aldol condensation reaction.

The physical properties of the solutions of polyacrylonitrile (PAN) in N,N -dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) were characterized in terms of solubility parameter. The physical properties were largely determined by individual solubility parameters, particularly the polar term, rather than overall solubility parameter. With increasing temperature, the intrinsic viscosity and hydrodynamic diameter of dilute solutions were decreased but the dynamic viscosity ( η ′) of concentrated solutions was increased. Of the two solvents, these phenomena were more pronounced with DMF; DMF gave greater η ′ and yield stress than DMSO. When the polymer solutions were dried at 25 °C DMSO generated a cocontinuous structure whereas DMF produced a dispersed morphology. In addition, DMF dissolved PAN faster than DMSO, and the dissolution process followed a mechanism analogous to S N 2 reaction.

An in-line device for measuring the water content in ethanol was developed using a polyvinyl alcohol (PVA)-coated quartz crystal microbalance. Bio-ethanol is widely used as the replacement of gasoline, and its water content is a key component of its specifications. When the PVA-coated quartz crystal microbalance is contacted with ethanol containing a small amount of water, the water is absorbed into the PVA increasing the load on the microbalance surface to cause a frequency drop. The determination performance of the PVA-coated microbalance is examined by measuring the frequency decreases in ethanol containing 2% to 10% water while the ethanol flows through the measurement device. The measurements indicates that the higher water content is the more the frequency reduction is, though some deviation in the measurements is observed. This indicates that the frequency measurement of an unknown concentration of water in ethanol can be used to determine the water content in ethanol. The PVA coating is examined by microscopy and FTIR (Fourier transform infrared) spectroscopy.

Lots of studies have been carried out to improve the strength of polyvinyl alcohol (PVA) fibers. One of these studies is crosslinking spinning for a good quality fiber. As a crosslinking agent, boric acid (BA, H3BO3) was used. PVA can crosslink with BA without adding cation in using dimethyl sulfoxide (DMSO). The effects of BA addition and molecular weight (MW) on the formation of the physical structure in PVA/DMSO solutions were investigated. The results showed that the time dependence of the rheological responses was greatly influenced by the BA addition to the PVA/DMSO solutions. The results also showed that the BA addition to the PVA/DMSO solutions increased the dynamic viscosity (η′), the storage modulus (G′), and the loss modulus (G″) of the PVA/DMSO solutions. Increasing MW of PVA also decreased the time dependence. In addition, the BA addition to the PVA/DMSO solutions decreased the gelation time of the PVA/DMSO solutions. These overall results suggested that the structure formation through specific interactions between PVA molecules and BA resulted in the time dependent changes of the rheological properties of the PVA/DMSO solutions.

The aim of this study was to investigate the DNA content and morphological characteristics of muscle fibers, and their relation to the growth performance in random bred control (RBC) and heavy weight (HW) Japanese quail lines. The 2 lines were of similar embryo size at 6 and 8 d of incubation; however, HW quail were significantly larger than their counterparts after 10 d of incubation (P < 0.05). The hatch weight of the HW quail line was approximately 1.3-fold higher than the RBC quail line (P < 0.001). After 15 d posthatch, the BW and pectoralis major muscle weight (PMW) exhibited remarkable differences between the 2 quail lines. The RBC line showed a faster rate of increase in PMW (2.7- vs. 2.1-fold) and total DNA mass (2.2- vs. 1.6-fold) between 0 and 4 d posthatch. The HW line exhibited a greater rate of the PMW (33.0- vs. 12.9-fold) and total DNA mass (10.3- vs. 4.0-fold) between 4 and 15 d posthatch than the RBC line. Moreover, the greatest increase in total DNA mass occurred between 0 and 8 d posthatch for the RBC line and 4 to 15 d posthatch for the HW line. These differences in the DNA content indicate a difference in the hypertrophic potential of muscle fibers between the 2 quail lines. The cross-sectional area of muscle fibers was 1.3-fold greater in the HW line compared with the RBC line at 8 d posthatch (158.5 vs. 97.11 μm(2), P < 0.001), and this difference increased with age (over 2.1-fold greater in the HW line). Thus, the most important time windows affecting ultimate body and muscle weights in the RBC and HW quail lines are between 0 to 8 d and 4 to 15 d posthatch, respectively. Rapid muscle growth rate and a greater muscle mass in the HW quail line may be partially due to the hypertrophic potential of muscle fibers, which is characterized by larger fiber size.

소형 충전물을 이용한 수평형 증류 장치를 제작하여 실험실 규모의 증류실험을 실시하였다. 직경 6.7 mm Raschig 링 형태의 스테인레스 스틸 충전물을 넣은 40 mm 직경의 유리관을 증류탑으로 사용하였다. 증류관의 길이 방향으로 5개의 독립된 전기가열기를 배열하여 증류관 내부 온도를 분리 조절할 수 있도록 하였다. 증류관 내의 온도가 길이에 따라 연속적으로 변화하도록 조절함으로써 각각의 온도에 상응하는 기-액 평형을 형성하여 분리가 가능하도록 하였다. 증류실험의 결과 증류관의 증류단 상당길이(HETP)가 수직형 증류관에 비해 큰 것을 알았으며, 실용화가 가능한 처리용량과 분리효율을 얻었다. 【A lab-sized distillation experiment was conducted using small-size packings and a horizontal distillation column. The 6.7 mm Raschig ring type packings of stainless steel and a 40 mm glass column were used, and five independent electric heaters were installed in the axial direction to adjust the column inside temperature separately. The temperature was continuously distributed along the column length to provide equivalent equilibrium to the temperature for the separation. From the experimental results, a larger HETP of the column than the vertical distillation column was obtained, but it was found that the practical separation with proper processing capacity and separation efficiency was available.】

Nylon-66 was melt compounded with 5 wt% nanosized organoclay varying the mixing rate and mixing time and their effects on the structure and properties of the nanocomposites were discussed in terms of the dispersion state of nanoclay. For the preparation of the nanocomposites, the total apparent shear (mixing rate × mixing time) was fixed to 450 at three different combinations of mixing rate (30, 60, 90 rpm) and mixing time (5, 7.5, 15 min). While the pristine organoclay showed a (001) peak at 2θ = 4.9° in the WAXD patterns, nylon-66/clay nanocomposites gave the disappearance of the peak regardless of mixing conditions, suggesting an exfoliated clay morphology in the nylon 66 matrix. The exfoliation of nanoclay in the nylon-66 matrix was also demonstrated by TEM measurements. On the contrary, rheological measurements revealed that the dispersion state of nanoclay was significantly influenced by the preparation conditions. The dynamic viscosity (η) of nylon-66/clay nanocomposites was increased as mixing rate was increased. For the normalized viscosity (η′(t)/η′(0)) obtained by time sweep at a given frequency, all the nanocomposites presented a decreased and upturned trend at the measuring time of ca. 500 s, while nylon-66 showed an increased one over the entire time range. Nylon-66/clay nanocomposites gave lower value of tanδ with increasing mixing rate. In the logarithmic plot of storage modulus versus loss modulus, the nanocomposites prepared at higher mixing rate gave smaller slope, indicative of an increased heterogeneity. Nanoclay played a role of nucleating agent for nylon-66 by increasing the crystallization temperature, which was more pronounced at lower mixing rate. The induction time rheologically obtained from time sweep measurement at 1 rad/s at 235°C was shorter for the nanocomposites prepared at lower mixing rate, but at 3 rad/s it was little affected by the preparation conditions.

In the manufacture of baby food in the form of semi-solid to give the most suitable rheological properties to select thickener, 4% of rice flour, modified starch 1 and modified starch or 0.3% pectin added to baby food. After 3 minutes at a pressure 550 MPa high pressure processing(HPP), sensory evaluation conducted to measure the viscosity results, the addition of rice flour, baby food bananas and apples all the color, texture, flow properties and high affinity for most commercial baby food as well as the most likely to show the viscosity of semi-solid state in the manufacture of baby food there were rice flower most suitable. The baby food that 4%, 6% and 8% of rice flower added as thickener were high pressure processing at 450 MPa and 550 MPa pressure and 1, 3 and 5 min conditions. In results, the higher added percentage of rice flower, the viscosity and lightness were increased, pH and sugar content were not significantly different from. In addition, ultra-high pressure processing conditions and the processing time for a change in pressure due to the increase is not significantly different. Because of high-pressure processing does not significantly affect the physical properties of the baby food, consideration of the economy and gelatinization degree, high-voltage processing conditions for the manufacture of baby food 550 MPa, 3 min was considered the most suitable processing conditions.

The UV photopolymerization of trimethylolpropane triacrylate with a photoinitiator of 2-ethylanthraquinone is monitored using the variation of resonant resistance of a quartz crystal resonator to investigate the polymerization kinetics. The roles of initiator concentration and irradiation time are experimentally examined, and it is found that two different kinetics are involved in the photopolymerization. The initiator radicals produced by the UV light proceed the polymerization as long as the monomer remains even after the UV illumination has stopped. The experimental results indicate that the photopolymerization has the first-order kinetics at the first- and the zeroth-order kinetics followed. With the high concentration of initiator the polymerization occurs in the first-order kinetics only, and so does with long irradiation time. The polymerization constants of the first and zeroth-order kinetics are estimated from monitoring monomer amounts at different polymerization conditions. The photopolymerization is characterized with the FTIR spectroscopy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A new monitoring device for the nonisothermal crystallization of thermoplastic polymers, polyethylene, polypropylene, polystyrene, and polyamide, is developed utilizing a quartz crystal resonator, and its performance is evaluated by comparing the measurements with the results of DSC thermoanalysis and microscopic observation. The experimental results of four different polymers indicate that the variation of resonant freency of the quartz crystal resonator is a good means to monitor the crystallization process. Though the measurements of melting and crystallization are close to the DSC outcome, more deviation is observed with the new device. The change in crystalline morphology during the crystallization process is also detected from the slope changes of the frequency decrease. In comparison with the microscopic observation of polymer films, it is found that the processes of nucleation and crystal growth in nonisothermal crystallization can be explained with the variation of the resonant frequency of the quartz crystal resonator. In addition, crystallization kinetics is modeled with the Avrami equation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The effects of the interface affinity between the nanoparticle and polymer matrix on the rheological properties of nanoparticle suspended-polymer solutions were investigated. Two polymers, polar polyacrylonitrile (PAN) and nonpolar polystyrene (PS), were selected, and the cosolvent was N,N-dimethylacetamide and 0.1∼5 wt% of polar ZnO nanoparticles in the polymer were used. The inclusion of ZnO notably increased the viscosity (γ′) of the PAN solutions, even at such a low loading level of 0.1 wt%. A maximum value of γ′ was observed at a 1 wt% of ZnO content. On the other hand, the γ′ of the PS solutions decreased with increasing ZnO content. Both the PAN and PS suspension systems exhibited a notable decrease in γ′ above a critical ZnO content. Although the PAN solutions showed a lower loss tangent (tanδ) at higher ZnO contents, the PS solutions containing > 2 wt% ZnO showed higher tanδ above a frequency of 2 rad/s. On the Cole-Cole plot, the PAN solutions did not give a single master curve depending on the ZnO content. However, the PS solutions showed little scattering from the master curve of a slope of ca. 1. ZnO increased the relaxation time of the PAN solutions but decreased the relaxation time of the PS solutions. Open image in new window

The aim of this study was to investigate the variations in myosin heavy chain (MHC) isoformcontent, muscle fiber type composition, and meat quality traits in pork groups that werecategorized by total protein solubility (TPS). Additionally, this study focused on individualpostmortem protein changes using two-dimensional electrophoresis (2-DE) based proteomeanalysisintheporcinelongissimusdorsimusclescategorizedbyTPS.ThelowTPSgroupshowedhigherpercentagesoftheMHCfastisoform(P

A new device for measuring the pore characteristics of adsorbents is developed for fast measurement and convenient sample handling. The proposed device utilizes a quartz crystal resonator capable of detecting the change of mass loading in nanogram scale. The measured material is coated on the electrode surface of the resonator, and the change of resonant frequency of the resonator at different pressures of adsorbate gas is converted into the adsorbed amount used in the computation of the adsorption surface area and pore size. For the performance evaluation of the device, alumina and activated carbon are tested with the adsorbate, i-butane. The experimental results show that the proposed device gives comparable measurements with some deviation to the reference values of the adsorption characteristics. It is proved that the device is relatively simple and requires short measurement time and the mild condition of sample handling.

Aims: To evaluate the effectiveness of organic acids and supercritical carbon dioxide (SC-CO2) treatments as well as their combined effect for the reduction of nonpathogenic Escherichia coli and three pathogenic bacteria in fresh pork. Methods and Results: The different treatment conditions were as follows: (i) treatment with acetic (1%, 2% or 3%) or lactic acid (1%, 2% or 3%) only, (ii) treatment with SC-CO2 at 12 MPa and 35°C for 30 min only and (iii) treatment with 3% acetic or lactic acid followed by treatment with SC-CO2. Within the same organic acid concentration, the lactic and acetic acid treatments had similar reductions. For the combined treatment of lactic acid and SC-CO2, micro-organism levels were maximally reduced, ranging from 2·10 to 2·60 log CFU cm−2 (E. coli, 2·58 log CFU cm−2; Listeria monocytogenes, 2·60 log CFU cm−2; Salmonella typhimurium, 2·33 log CFU cm−2; E. coli O157:H7, 2·10 log CFU cm−2). Conclusions: The results of this study indicate that the combined treatments of SC-CO2 and organic acids were more effective at destroying foodborne pathogens than the treatments of SC-CO2 or organic acids alone. Significance and Impact of the Study: The combination treatment of SC-CO2 and organic acids may be useful in the meat industry to help increase microbial safety.

To trace the plasticizing effects of propylene glycol (PG) on poly(vinyl alcohol) (PVA), the rheological properties of PVA solutions in dimethyl sulfoxide (DMSO) and the physical properties of PVA films were discussed in terms of PG content. Both properties were closely related to the hydrogen bond breaking effects of PG. The 6 and 12 wt% PVA solutions containing PG exhibited Bingham behavior, which was more noticeable at lower plasticizer content and higher polymer concentration. The 6 wt% PVA solutions containing more than 30 wt% PG showed a sudden decrease of viscosity over the frequency range of 0.08 and 0.2 rad/s. However, the 12 wt% PVA solutions showed no viscosity reduction even at a PG content up to 40 wt%. The glass transition temperature of the PVA/PG films was almost linearly decreased with increasing PG content but an abrupt reduction was observed at a plasticizer content 30 wt%, suggesting that the hydrogen bond breaking effects of PG on PVA became dominant between 20 and 30 wt%. This effect was further supported by the similar tendency of the tensile properties.

The side chain liquid crystal triblock copolymers (TBCs), which underwent phase transitions below their decomposition temperature, were prepared by copolymerization of poly(n-butyl acrylate) and a comonomer containing the mesogenic azobenzene group. The physical properties of TBCs in the distinctive transition temperature ranges were investigated in terms of the liquid crystal (LC) content in the copolymers. The phase transition temperatures traced optically, thermally and rheologically were well coincided one another and clearly exhibited the phase transition of smectic-nematic-isotropic with increasing temperature. In the smectic phase, increasing temperature made the liquid crystal system more elastic, but viscosity (η′) remained almost constant. In the nematic phase, increasing temperature abruptly decreased η′ andG′, ultimately leading to isotropic phase. Both smectic and nematic phases exhibited Bingham viscosity behavior but the former gave much greater yield stress at the same LC content.

The effects of organoclay and polyhedral oligomeric silsesquioxanes (POSS) nanoparticles on the crystallization behavior of high molecular weight poly(ethylene terephthalate) (HMWPET; inherent viscosity of 1.05) were investigated in terms of nanoparticle content and shear rate. Both nanoparticles played a role of nucleating agent for PET and increased the cold crystallization temperature by about 24°C. The half-time of crystallization was also decreased with increasing the nanoparticle content. Clay proved to be more effective than POSS; a notable nucleating effect was observed at 0.3 wt% for clay and 2 wt% for POSS. Introducing 1 wt% of clay gave the highest crystallization rate among all PET nanocomposite samples examined. Isothermal crystallization of the nanocomposites under dynamic shear exhibited similar crystallization behavior. As in the DSC measurement, clay appeared to be more effective to promote the crystallization of PET under shear. The nucleating effects were more noticeable at higher shear rate. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

The objective of this study was to examine the Sarcodon aspratus extract including protease how to affect tenderness of the bovine longissimus dorsi muscle. In addition, we investigated myofibrillar protein fragmentation, particularly in myosin, and its influence on meat tenderness. Beef loin chunks were marinated with 0.5 g/100 g, 1 g/100 g, and 2 g/100 g powdered S. aspratus extract, 0.2 g/100 mL papain, and distilled water (control), respectively. Although tenderness of meat is increased by adding S. aspratus extract, differences in meat quality traits, such as muscle pH and meat color, were small and not considered to have practical importance between the control and enzyme-treated samples. Furthermore, the S. aspratus extract influenced the myofibril fragmentation index (MFI) as well as protein solubility. The changes in MFI and protein solubility were due to the myofibrillar protein degradation. Through Western blotting, we found that the S. aspratus extract, as well as papain, caused fragmentation of the myosin heavy chain, but the mushroom extract induced more fragmentations of myofibrillar proteins, and caused more tender meat.

Dye is difficult to remove from aqueous solution with common adsorbents due to its large molecular size. Mesoporous bamboo activated carbon is utilized in the adsorption of Black 5, Red E and phenol. The adsorption performance of the carbon is experimentally examined along with the characterization of the adsorbent. The comparison of adsorption capacity of the bamboo activated carbon with that of coconut activated carbon and carbon cryogel indicates that the large volume of mesopore in the carbon helps the expansion of adsorption capacity. Microscopic observation, the measurement of pore characteristics and fitting to the adsorption isotherms are conducted in the characterization of the bamboo activated carbon.

High molecular weight poly(ethylene terephthalate) (HMW-PET) (intrinsic viscosity of 0.809 dL/g) and its nanocomposites with 1 wt.% organoclay C12PPh-Cl− and 1 and 2 wt.% trisilanol isobutyl-poly(hedral oligomeric silsesquioxane) (POSS) were high-speed melt spun over the range of take-up speeds 1 to 4.5 km/min, and the effects of nanoparticle type on the fiber properties were investigated. The clay and POSS nanocomposites exhibited quite different melt spinning behaviors. The neat PET and PET/POSS nanocomposites showed a neck-like deformation distinctly from the take-up speed of 3.5 and 3 km/min while PET/clay nanocomposites did not show any neck-like deformation over the entire spinning speed range. In comparison with nanocomposite chips clay gave rise to re-aggregation of nanoparticles whereas POSS made little change in dispersion. Clay suppressed the crystallization of PET during high-speed spinning although it had more effective nucleation effects at the static state than POSS. Clay nanocomposite fibers gave lower modulus and higher elongation at break than PET fibers. On the other hand, the mechanical properties of POSS nanocomposite fibers were almost equal or slightly better than PET fibers.

The objective of this study was to investigate the effect of supercritical carbon dioxide (SC-CO2) treatment for the sterilization purpose on meat quality and protein denaturation of the porcine longissimus dorsi muscle. The conditions of SC-CO2 treatment were 7.4 and 15.2 MPa at 31.1 °C for 10 min. SC-CO2 treatment had no effect on muscle pH, tenderness, and water-holding capacity (WHC). However, the samples treated at 7.4 MPa had a higher lightness value (52.97 vs. 46.94, P

A monitoring device for the phase transition of polymer material with temperature variation is developed utilizing a quartz crystal resonator, and its performance has been evaluated by implementing in the melting and crystallization of polyethylene. The observation is compared with the result of DSC thermo-analysis. The experimental outcome indicates that the resonant frequency variation shows not only the temperature of melting and crystallization, but the phase transition temperature of monoclinic to hexagonal phase.

A sensitivity determination method for a quartz crystal resonator is proposed, and its performance is examined with mass loading in gas and liquid phase applications. For the deposition of a known amount of mass on the resonator surface, dilute solutions of sodium chloride and stearic acid are utilized in air and water measurements, respectively. The resonator surfaces loaded with the practical materials are also observed with a microscope for the inspection of the material deposition. In both measurements, a linear relation of frequency drop and mass loading is yielded up to a loading of 150 ng, and a slightly lower sensitivity is obtained with more loading due to the base frequency reduction. The sensitivities are found to be 0.99 and 1.00 ng/Hz in air and in water applications, respectively. It is also demonstrated that the proposed technique is relatively simple in the measurement of sensitivity both in gas and in liquid phase utilizations.

The aims of this work were to compare the effects of dehairing methods and sex on pork quality and cold storage stability. For this study, one half of40 pigs were dehaired by scalding in the same abattoir, and the other half by dehiding. Each treatment consisted of one half gilts and one half castrated male pigs. Meat quality traits were measured at 24 hr after slaughter, and thiobarbituric acid (TBA), metmyoglobin contents and total plate counts (TPC) were evaluated at 1, 7, 14 and 21 days of cold storage. The carcass weight and backfat thickness of pigs dehaired by scalding were significantly higher than those dehided (p

The objective of this study was to investigate the effects of dehairing methods and sex on various traits of pork quality, as well as on tissue levels of the boar taint compounds androstenone and skatole. At the early postmortem period, dehided pigs showed higher muscle pH levels (p

The effects of diethyl glycol (DEG) on the rheolgical properties of polyvinyl alcohol(PVA) solutions in dimethyl sulfoxide and on the physical properties of PVA films were investigated. DEG seemed to change the state of hydrogen bonding in the solutions and in the films. In the case of 6 wt% PVA solutions, incorporating DEG abruptly reduced shear viscosity if DEG content exceeded 30 wt% to PVA whereas a little decrease of them was observed in 12 wt% PVA solutions over the DEG content observed. Further, at the same DEG content 6 wt% PVA solutions showed a more notable increase of viscosity with time at a constant shear rate than 12 wt% solutions. Dynamic mechanical thermal analysis revealed that introducing DEG broadened the peak of tan δ curve and lowered the glass transition temperature of PVA. DEG imparted toughening effects to PVA film preferably in the range of 10 to 20 wt% to PVA.

The effects of molecular weight distribution (MWD) on the rheological responses of shear-induced structural formation in the general-purpose polyvinyl alcohol (PVA) solutions dissolved in dimethyl sulfoxide (DMSO) were investigated. On the whole, time-dependence of rheological properties was more influenced by the PVA solutions with broad MWD at the similar weight average molecular weight (Mw). The dynamic viscosity (η′) of PVA/DMSO solution with broad MWD was lower than that with narrow MWD at the similar Mw until the second time sweep (T2) of PVA/DMSO solution. After the time-sweep experiment was repeated, the η′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. The G′ until 5 min of relaxation of PVA/DMSO solution with broad MWD was lower than that of PVA/ DMSO solution with narrow MWD at the similar Mw. After the time-sweep experiment was repeated, the G′ of PVA/DMSO solution with narrow MWD was lower than that of PVA/DMSO solution with broad MWD at the similar Mw. It could be interpreted as a consequence of the formation of three-dimensional gel structure through the polar interactions by hydroxyl groups whose strength was dependent on shearing conditions and MWD.

This study was designed to investigate the effects of KH-305 on erectile dysfunction in young rats, via nitric oxide (NO)-cGMP pathways. After oral administration of the KH-305 mixture (50, 100, 200, 300 mg/kg) to young rats for 10 days, NOS and SOD protein expressions in penile tissue and testosterone in plasma were measured. cGMP degradation was also investigated using bovine vascular smooth muscle cells pretreated with an NO donor, S-nitroso-N-Acetylpenicillamine (SNAP). The penile expression levels of nNOS and eNOS-dependent NOS activities as well as SOD preventing oxidative stress by overproduction of NO were increased significantly. Also, the concentration of testosterone in the plasma was increased. In vitro, cGMP concen-trations were decreased dose dependently in the KH-305. These results suggest that KH-305 may be useful in erectile dysfunction.

A crystallization monitoring system using a quartz crystal oscillator was utilized to predict different shapes of crystal formation by measuring crystal growth rate and to measure supersaturation. Applying different rates of cooling, crystal formation of different shapes was induced, and the frequency variation of the oscillator and the crystal shape observed with an SEM were compared to determine how the frequency variation can be interpreted for the prediction of produced crystal shape. The experimental results obtained from the crystallization of potassium nitrate and cupric sulfate solutions showed that the proposed frequency measurement technique could be applied in the prediction of crystal shape of cooling crystallization processes. In addition, supersaturation was determined from the measurements of solution and coolant temperatures.