Electrospun poly(acrylic acid)/lysine fibers and the interactive effects of moisture,heat, and cross‐link density on their behavior

Poly(acrylic acid) (PAA) is an important polymer frequently used as a superabsorbent in health and hygiene products. As a polyelectrolyte that swells with absorption of water it has potential application in other fields including drug delivery, tissue scaffolds, actuators, and desiccation and humidity control. To be useful in such applications the membrane's mechanical integrity must be maintained while optimizing its moisture absorption properties. In this work PAA membranes are electrospun with lysine as cross‐linking agent. The effects of varying the concentration of the lysine on the cross‐link density and consequently on the thermo‐ and hygro‐mechanical properties of the membranes are studied through electron microscopy, FTIR spectroscopy, and dynamic mechanical thermal analysis (DMTA). Isothermal glass transitions are shown to occur with varying moisture content. The moisture content (or relative humidity) at which the transition occurs is reduced by increasing temperature and can be controlled by varying the cross‐link density. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41252.     

Technical note: A comparison of 2 methods of assessing lameness prevalence in tiestall herds

We compared 2 methods for identifying lame cows and estimating the prevalence of lameness in tiestalls. Cows (n = 320) in 9 tiestall herds were scored as lame both by the presence of limping while walking and by stall lameness scores (SLS). The SLS was based on the number of the following behaviors that the cow showed while standing in the tiestall: weight shifting, standing on the edge of the stall, uneven weight bearing while standing, and uneven weight bearing while moving from side to side. Two observers watched video-recordings of the cows. Intraobserver agreements for the 4 SLS behaviors ranged from 92 to 100%, and interobserver agreement ranged from 81 to 100%. The overall prevalence of lameness based on an SLS of ≥2 was similar to that of limping (39 vs. 40%). The sensitivity of the classification based on the SLS was 0.63 and the specificity was 0.77 in identifying cows with a limp; accuracy varied across farms from 62.2 to 80.4%, with a mean of 71.7%. A cow with an SLS of ≥2 had 4.88 times the odds of limping than a cow with an SLS of <2. The prevalence of lameness on farms based on SLS was highly correlated with the prevalence of limping (Pearson correlation = 0.88; n = 9), and prevalence estimates from the 2 methods diverged most when the mean herd prevalence was lower. The SLS method provides an estimate of the prevalence of lameness in tiestall herds comparable with traditional gait scoring, but does not require that the cows be untied. The SLS method could be used to improve lameness detection on tiestall farms and obtain estimates of lameness prevalence without the need to walk the cows.     

Water proton T 1 measurements in brain tissue at 7, 3, and 1.5T using IR-EPI, IR-TSE, and MPRAGE: results and optimization

Method This paper presents methods of measuring the longitudinal relaxation time using inversion recovery turbo spin echo (IR-TSE) and magnetization-prepared rapid gradient echo (MPRAGE) sequences, comparing and optimizing these sequences, reporting T ₁ values for water protons measured from brain tissue at 1.5, 3, and 7T. T ₁ was measured in cortical grey matter and white matter using the IR-TSE, MPRAGE, and inversion recovery echo planar imaging (IR-EPI) pulse sequences. Results In four subjects the T ₁ of white and grey matter were found to be 646±32 and 1,197±134ms at 1.5T, 838±50 and 1,607±112ms at 3T, and 1,126±97, and 1,939±149ms at 7T with the MPRAGE sequence. The T ₁ of the putamen was found to be 1,084±63ms at 1.5T, 1,332±68ms at 3T, and 1,644±167ms at 7T. The T ₁ of the caudate head was found to be 1,109± 66ms at 1.5T, 1,395±49ms at 3T, and 1,684±76ms at 7T. Discussion There was a trend for the IR-TSE sequence to underestimate T ₁ in vivo. The sequence parameters for the IR-TSE and MPRAGE sequences were also optimized in terms of the signal-to-noise ratio (SNR) in the fitted T ₁. The optimal sequence for IR-TSE in terms of SNR in the fitted T ₁ was found to have five readouts at TIs of 120, 260, 563, 1,221, 2,647, 5,736ms and TR of 7 s. The optimal pulse sequence for MPRAGE with readout flip angle = 8° was found to have five readouts at TIs of 160, 398, 988, 2,455, and 6,102ms and a TR of 9 s. Further optimization including the readout flip angle suggests that the flip angle should be increased, beyond levels that are acceptable in terms of power deposition and point-spread function.     

Monitoring eye movements under conditions of associative matching, response production, and stimulus and response production.

Monitored eye movements in each of 3 studies with 20, 19, and 18 undergraduates, respectively, while Ss were given 8 study trials on a 7-item paired-associate list. Ss were then subjected to a single test trial of associative matching (Exp. I), response production (Exp. III) or stimulus and response production (Exp. IV). A 4th study with 42 Ss, (Exp. II), without eye movement monitoring, involved 3 groups of Ss given either 2, 4, or 6 study trials followed by a single test trial of associative matching. Results, with the exception of Exp. I, were generally consistent with a 2-stage notion of verbal paired-associate learning. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monitoring eye movements during paired-associate learning in a retroactive inhibition setting.

Monitored eye movements during the learning and relearning of a 7-pair A-B list for 64 undergraduates in 4 groups, 2 of these being required to learn an AC list in the interim and 2 being given interpolated activity designed to produce minimal interference with the relearning of A-B. Retroactive inhibition was demonstrated and the fixation and eye-movement data for original learning were consistent with earlier studies and with a 2-stage interpretation of paired-associate learning. The visual monitoring data for relearning were more compatible with a selector mechanism account of retroactive inhibition than with one of competition, unlearning, or trace decay. (French summary) (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of Reference Foods in Repeated Acceptability Tests: Testing Familiar and Novel Foods Using 2 Acceptability Scales

ABSTRACT:  Hedonic tests are routinely used to assess the acceptance of food products. However, these single tests may not be the best approach for predicting long-term use. The objectives of this study were, first, to check whether a difference from reference score is more sensitive to changes in hedonic scores, second, to assess whether the labeled affective scale (LAM) is more sensitive to differences than the 9-point scale, and third, to assess the effect of repeated exposure on the hedonic scores of neophilic and neophobic panelists for familiar and novel foods. Two groups of 41 panelists were tested with either the 9-point hedonic scale or LAM scale. Panelists received a food neophobia questionnaire and were subsequently classified to neophobic, neophilic, or neutral. Ten foods, including 5 novel and 5 familiar, were used. In each session, 5 to 6 foods were served twice/week for 4 wk. Serving frequency ranged between 1 and 8 times (1, 2, 4, 6, 8). Data analyses were performed 3 times, using either absolute acceptability scores or relative scores, that is, the difference between absolute scores and scores for either the reference (cracker, RELFAM) or a novel food (pickled-ginger, RELNOV) served in every session. The 3 analyses (absolute, RELFAM, and RELNOV) generated similar results with respect to the number of significant differences between foods. There was no major drift in acceptability scores with sessions. A significant food effect was obtained ( P < 0.05) and a significant food × neophobia ( P < 0.05) was noted for 2 novel foods, pickled ginger, and lychee, whereby neophobic panelists were less accepting of them. Both scales were equally sensitive with some advantages for LAM over the 9-point hedonic scale.     

“实验探究式”教学应用探究

随着社会的发展和进步,传统的教学方法在实际教学中的弊端愈发明显,教学方法的改革和创新是大势所趋,也是提高教学质量的根本;同时技工学校的化学教学还面临着学生基础差,学习兴趣差等问题,改变教学方法提高教学质量是我一直努力的目标,我在化学教学运用"实验探究式"教学,对传统的化学教学方法的改进与创新进行了一些有益的尝试。     

Sodium (23Na) ultra-short echo time imaging in the human brain using a 3D-Cones trajectory

Object

Sodium magnetic resonance imaging (²³Na-MRI) of the brain has shown changes in ²³Na signal as a hallmark of various neurological diseases such as stroke, Alzheimer’s disease, Multiple Sclerosis and Huntington’s disease. To improve scan times and image quality, we have implemented the 3D-Cones (CN) sequence for in vivo ²³Na brain MRI.

Materials and methods

Using signal-to-noise (SNR) as a measurement of sequence performance, CN is compared against more established 3D-radial k-space sampling schemes featuring cylindrical stack-of-stars (SOS) and 3D-spokes kooshball (KB) trajectories, on five healthy volunteers in a clinical setting. Resolution was evaluated by simulating the point-spread-functions (PSFs) and experimental measures on a phantom.

Results

All sequences were shown to have a similar SNR arbitrary units (AU) of 6–6.5 in brain white matter, 7–9 in gray matter and 17–18 AU in cerebrospinal fluid. SNR between white and gray matter were significantly different for KB and CN (p = 0.046 and <0.001 respectively), but not for SOS (p = 0.1). Group mean standard deviations were significantly smaller for CN (p = 0.016). Theoretical full-width at half-maximum linewidth of the PSF for CN is broadened by only 0.1, compared to 0.3 and 0.8 pixels for SOS and KB respectively. Actual image resolution is estimated as 8, 9 and 6.3 mm for SOS, KB and CN respectively.

Conclusion

The CN sequence provides stronger tissue contrast than both SOS and KB, with more reproducible SNR measurements compared to KB. For CN, a higher true resolution in the same amount of time with no significant trade-off in SNR is achieved. CN is therefore more suitable for ²³Na-MRI in the brain.     

HPLC-ESI-MS/MS characterization of phenolics in <Emphasis Type="Italic">prunus amygdalus</Emphasis>, cultivar “umm alfahm” and its antioxidant and hepatoprotective activity

Metabolite profiling of the total ethanolic extract of Prunus amygdalus stem and leaves was carried out for the first time using LC-DAD-ESI-MS in the negative ion mode to investigate its chemical composition. Results revealed the identification of 33 phenolic compounds. Fifteen compounds were investigated in P. amygdalus for the first time and identified as; veratic acid, rosmarinicacid, protocatechuic acid-hexoside, 3-O-caffeoylquinic acid (neochlorogenic acid), dihydroquercetin- hexoside, coumaroyl-quinic acid, vanillic acid glucoside, cis piceid, hesperidin, dihydrokaempferol, acteoside, quercetin acetyl hexoside, homovanillic acid, fisetin-deoxyhexoside. The antioxidant potential of the total ethanolic extract (EE) and the fractions: petroleum ether (PE), chloroform (CE), ethyl acetate (EtE), methanol eluted diaion (DME) and diaion eluted with 50% methanol (D 50%E) was performed using DPPH assay. The most potent antioxidant EE, EtE and D50%E extracts (compared with vitamin C) were selected for further hepatoprotective assessment against hepatotoxicity induced by thioacetamide in a dose of 200 mg/kg compared with silymarin (50 mg/kg) as a standard drug. Results revealed the significant reversal of the deleterious effects of thioacetamide on serum ALT, AST and total protein in the order: EtE >?(Silymarin?=?EE)?>?D50% E. The biochemical results were corroborated with the histological studies of liver.