Authors:J. Wang, J. Chen, F. Dai, F. Wu, J. Yang, and G. Zhang
The effects of sowing date, nitrogen application level and timing on barley protein components and malt quality were investigated. There was a significant difference in total protein and its protein fractions among the four barley genotypes. The protein component was changeable over the different growing conditions, and the extent of change varied with protein fraction and genotype. Marked variation in malt quality over the different environments (sowing date, N fertilizer rate and applying time) was also observed. Increased N fertilizer application increased diastatic power (DP) value, but reduced malt extract. Grain protein content was significantly and positively correlated with albumin, globulin and hordein, but was not correlated with glutelin. However, glutelin was significantly related to other malt quality parameters.
Authors:Z. Wu, F. Li, L. Huang, Y. Shi, X. Jin, S. Fang, K. Chuang, R. Lyon, F. Harris, and S. Cheng
The thermal mechanical properties and degradation behaviors were studied on fibers prepared from two high-performance, heterocyclic polymers, poly(p-phenylenebenzobisthiazole) (PBZT) and poly(p-phenylenebenzobisoxazole) (PBZO). Our research demonstrated that these two fibers exhibited excellent mechanical properties and outstanding thermal and thermo-oxidative stability. Their long-term mechanical tensile performance at high temperatures was found to be critically associated with the stability of the C—O or C—S linkage at the heterocyclic rings on these polymers' backbones. PBZO fibers with the C—O linkages displayed substantially higher thermal stability compared to PBZT containing C—S linkages. High resolution pyrolysis-gas chromatography/mass spectrometry provided the information of the pyrolyzates' compositions and distributions as well as their relationships with the structures of PBZT and PBZO. Based on the analysis of the compositions and distributions of all pyrolyzates at different temperatures, it was found that the thermal degradation mechanisms for both of these heterocyclic polymers were identical. Kevlar®-49 fibers were also studied under the same experimental conditions in order to make a comparison of thermo-oxidative stability and long-term mechanical performance at high temperatures with PBZO and PBZT fibers. The data of two high-performance aromatic polyimide fibers were also included as references.
Authors:T. Wu, W. Dai, G. Xiao, F. Shu, J. Yao, and J. Li
With the low permeability and high swelling property, Gaomiaozi (GMZ) bentonite is regarded as the favorable candidate backfilling
material for a potential repository. The diffusion behaviors of HTO in GMZ bentonite were studied to obtain effective diffusion
coefficient (De) and accessible porosity (ε) by through- and out-diffusion experiments. A computer code named Fitting for diffusion coefficient
(FDP) was used for the experimental data processing and theoretical modeling. The De and ε values were (5.2–11.2) × 10−11 m2/s and 0.35–0.50 at dry density from 1,800 to 2,000 kg/m3, respectively. The De values at 1,800 kg/m3 was a little higher than that of at 2,000 kg/m3, whereas the De value at 1,600 kg/m3 was significantly higher (approximately twice) than that of at 1,800 and 2,000 kg/m3. It may be explained that the diffusion of HTO mainly occurred in the interlayer space for the highly compacted clay (dry
density exceeding 1,300 kg/m3). 1,800 and 2,000 kg/m3 probably had similar interlayer space, whereas 1,600 kg/m3 had more. Both De and ε values decreased with increasing dry density. For compacted bentonite, the relationship of De and ε could be described by Archie’s law with exponent n = 4.5 ± 1.0.
Authors:Z. Wu, A. Zhang, D. Shen, M. Leland, F. W. Harris, and S. Z. D. Cheng
Three aromatic polyimides based on 3,3′,4,4′-biphenyl-tetracarboxylic dianhydride (BPDA) and three different diamines 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (PFMB), 2,2′-dimethyl-4, 4′-diaminophenyl (DMB) or 3,3′-dimethylbenzidine (OTOL) have been synthesized. These polyimides are soluble in hotp-chlorophenol,m-cresol or other phenolic solvents. Fibers have been spun from isotropic solutions using a dry-jet wet spinning method. The as-spun fibers generally exhibit low tensile properties, and can be drawn at elevated temperatures (>380° C) up to a draw ratio of 10 times. Remarkable increases in tensile strength and modulus are achieved after drawing and annealing. The crystal structures of highly drawn fibers were determinedvia wide angle X-ray diffraction (WAXD). The crystal unit cell lattices have been determined to be monoclinic for BPDA-PFMB and triclinic for both BPDA-DMB and BPDA-OTOL. Thermomechanical analysis (TMA) was used to measure thermal shrinkage stress and strain. A selfelongation has been found in the temperature region around 450°C. This phenomenon can be explained as resulting from the structural development in the fibers as evidencedvia WAXD observations.
Authors:H. Yang, N. Tan, F. WU, H. Liu, M. Sun, Z. She, and Y. Lin
The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0,
adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after
loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the
adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained
that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental
data for adsorption of uranium(VI).
Authors:Y. Li, F.Q. Lu, Y. Feng, Z.D. He, and X.L. Wu
Analysis of the binding interaction of (−)-epigallocatechin-3-gallate (EGCG) and pepsin is important for understanding the inhibition of digestive enzymes by tea polyphenols. We studied the binding of EGCG to pepsin using fluorescence spectroscopy, Fourier transform infrared spectroscopy, isothermal titration calorimetry, and protein-ligand docking. We found that EGCG could inhibit pepsin activity. According to thermodynamic parameters, a negative ΔG indicated that the interaction between EGCG and pepsin was spontaneous, and the electrostatic force accompanied by hydrophobic binding forces may play major role in the binding. Data from multi-spectroscopy and docking studies suggest that EGCG could bind pepsin with a change in the native conformation of pepsin. Our results provide further understanding of the nature of the binding interactions between catechins and digestive enzymes.
Authors:X. Wu, H. Cárcamo, B. Beres, F. Clarke, R. DePauw, and B. Pang
Host plant resistance in the form of wheat with the stem lumen filled with pith has been the main strategy to manage the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae) - a major pest of wheat in the northern Great Plains of North America. Recently a new source of resistance has been made available combining a single dominant solid pith gene from durum wheat (Triticum turgidum L. var. durum) with spring bread wheat cultivars. Our study had two objectives: (i) assess levels of C. cinctus damage and larval C. cinctus mortality in wheat with the novel solid germplasm, conventional solid-stems and susceptible cultivars; and (ii) determine plant genotype effects on populations of C. cinctus parasitoid Bracon cephi (Gahan) (Hymenoptera: Braconidae). The study was conducted in plots near Lethbridge, Alberta, Canada from 2003–2005. The novel solid-stemmed hexaploid G9608B1-L12J11BF02, solid-stemmed AC Eatonia and hollow-stemmed durum AC Navigator reduced the infestation level and girdling damage by C. cinctus. Another synthetic hexaploid B9973B03&AC4AW, hollow-stemmed AC Cadillac, McKenzie and AC Barrie were more susceptible to C. cinctus damage. Larval parasitism by B. cephi increased along with C. cinctus infestation levels. Stem solidness itself, regardless of source, had no direct negative effect on B. cephi but due to lower infestation and survival of C. cinctus in solid stem genotypes, the overall population of parasitoids was reduced. When planting monocultures of effective solid stem wheat, strategies to conserve populations of parasitoids should be considered for long term sustainable management of C. cinctus.
Authors:R. Wang, A. Chau, F. Liu, H. Cheng, P. Nar, X. Chen, and Q. Wu
The aim of this paper is to consider using effective natural minerals in studying the retardation and migration of radium under the influence of groundwater in the far-field of a radioactive waste repository. The properties of adsorbing radium by minerals are studied by adopting the static and dynamic adsorption method. Preliminary experimental results give confidence in the validity of using Maifanshih and barite to adsorb radium in water and to serve as effective retarding materials in radioactive waste repositories, their Kd values being 3815 and 2955, respectively. The study on a certain number of conditions of adsorbing radium by the promissing material Maifanshih is reported for the first time. The mechanism of radium adsorption has been discussed and modeling of migration of radium in the minerals has been presented to establish a rational basis for the longterm prediction required for safety assessment of underground disposal of radioactive waste.
Authors:G.P. Li, D. Zhou, L.N. Kan, Y.W. Wu, J.F. Fan, and J. Ouyang
The inhibitory effects of phytic acid (PA) on the browning of fresh-cut chestnuts and the associated mechanisms of PA on polyphenol oxidase (PPO) and peroxidase (POD) activities were investigated. The enzymatic browning of chestnut surfaces and interiors was suppressed by soaking shelled and sliced chestnuts in a PA solution. The specific activities of PPO and POD extracted from chestnuts declined due to inhibition by PA. PA was determined to be a competitive inhibitor of both PPO and POD by Lineweaver-Burk plots. The binding modes of PA with PPO and POD were analysed by AutoDock 4.2.
Authors:F. Gao, J. Bao, J. Xue, J. Huang, W. Huang, S. Wu, and Li-Fan Zhang
This study was designed to test the hypothesis that a medium-term simulated microgravity by tail-suspension (SUS) induces hypertrophic and atrophic changes in the common carotid artery and abdominal aorta with their innermost smooth muscle (SM) layers being most profoundly affected. The second purpose was to elucidate whether vascular local renin-angiotensin system (L-RAS) plays an important role in the differential remodeling of the two kinds of large arteries by examining the gene and protein expression of angiotensinogen (A
) and angiotensin II receptor type 1 (AT1R) and their localization in the vessel wall. The results showed that SUS induced an increase in the media thickness of the common carotid artery due to hypertrophy of the four SM layers and a decrease in the total cross-sectional area of the nine SM layers of the abdominal aorta without significant change in its media thickness. Irrespective of the nature of remodeling, the most prominent changes were in the innermost layers. Immunohistochemistry,
hybridization, Western blot, and real time quantitative PCR analysis revealed that SUS induced an up- and down-regulation in A
and AT1R expression in the common carotid artery and abdominal aorta, respectively. In conclusion, our findings have demonstrated some special features in the structural adaptation of large elastic arteries due to a medium-term simulated microgravity.