Search

Objective: The study aimed to optimize the preparation process and investigate the quality of coix bran dietary fiber. Methods: The coix bran was used as raw material; the effects of solid-liquid ratio, the amount of amylase and alcalase on the extraction rate were analyzed by usingorthogonal experiments. The chemical composition and physicochemical properties of the dietary fiber obtained under the optimal preparation conditions was analyzed. Results: The optimal extraction parameters of dietary fiber were as follows: solid-liquid ratio was 1∶10 (g/mL), the amount of amylase and alcalase was 100 U/g, respectively, and the extraction rate was up to 84.39%. The insoluble dietary fiber (64.49%) was significantly (P ＜ 0.05) improved compared to coxi bran. And the soluble dietary fiber was 0%, the content of moisture, fat, starch, and protein was significantly decreased (P ＜ 0.05). When the temperature increased, swelling capacity, water holding capacity and oil holding capacity were improved. and was 3.12 mL/g, 4.02 g/g and 4.29 g/g, respectively. Conclusion: The method could be used as a reliable method to extract the coix bran dietary fiber.

An ultra performance liquid chromatography – electrospray ionization triple-quadruple tandem mass spectrometric(UPLC–ESI MS /MS) method was developed for determining Quinololine antibiotics (Carbadox,, Quinocetone, Mequindox, Olaquindox, Cyadox, Tilmicosin, Tylosin, quinoxaline-2-carboxylic acid, 3-methylquinoxaline-2-carboxylic acid) and aminoglycoside antibiotics(Tilmicosin, Tylosin) residues in Penaeus. vannamei, Samples were extracted with acidified acetonitrile, then cleaned up with hexane. The separation of targets was carried out on a Waters BEH C18 column using acetonitrile and 0. 1% fomicacid as mobile phase. Analyte identification and quantification were performed by MS/MS under multiple-reaction monitering(MRM) mode with the external standard method. The results showed that there were good linear relationships between peak area and concentrations of nine targets in the range of 2.5 ~ 50 μg/L, with correlation coefficients more than 0. 999 and The limits of detection(LOD) were in the range of 0. 1 ~ 0.9 μg/kg. the recoveries ranged from 80.2% ~ 94.0%, with RSDs of 1.7%~8.4%. The method is simple, accurate and precise, and It could satisfy the requirement of mass and fast analysis in the laborator.

It still remains a great challenge to selectively enrich and sensitively quantify the trace volatile organic compounds (VOCs) in real samples with complex matrix. In this study, an integration method combining a selective enrichment medium of reduced graphene oxide (rGO) with a specially designed micro thermal-assisted purge-and-trap sampling device was developed for efficient enrichment and sensitive quantification of trace tobacco VOCs coupling with thermal desorption (TD)-gas chromatography/mass spectrometry (GC/MS). The prepared rGO has been proved to possess excellent enrichment selectivity and capacity for tobacco polar VOCs with the multi-layer structure, good thermal stability and large specific surface area. The specially designed sampling device was efficient and suitable for enriching and sampling trace polar tobacco VOCs coupling with rGO medium. Under the optimized sampling and analytical conditions, the established analytical method could be actually applied for quantification of typical tobacco polar VOCs with the good recoveries of 72.9–128% and the satisfied RSDs of 1.8–19.9% (n = 3). The results suggested that the developed method was selective, sensitive and reliable for enrichment and quantification of trace tobacco polar VOCs. [ABSTRACT FROM AUTHOR]

Photosynthesis constitutes the only known natural process that captures the solar energy to convert carbon dioxide and water into biomass. The primary reactions of photosynthesis are catalyzed by the photosystem II (PSII) and photosystem I (PSI) complexes. Both photosystems associate with antennae complexes whose main function is to increase the light-harvesting capability of the core. In order to maintain optimal photosynthetic activity under a constantly changing natural light environment, plants and green algae regulate the absorbed photo-excitation energy between PSI and PSII through processes known as state transitions. State transitions represent a short-term light adaptation mechanism for balancing the energy distribution between the two photosystems by relocating light-harvesting complex II (LHCII) proteins. The preferential excitation of PSII (state 2) results in the activation of a chloroplast kinase which in turn phosphorylates LHCII, a process followed by the release of phosphorylated LHCII from PSII and its migration to PSI, thus forming the PSI–LHCI–LHCII supercomplex. The process is reversible, as LHCII is dephosphorylated and returns to PSII under the preferential excitation of PSI. In recent years, high-resolution structures of the PSI–LHCI–LHCII supercomplex from plants and green algae were reported. These structural data provide detailed information on the interacting patterns of phosphorylated LHCII with PSI and on the pigment arrangement in the supercomplex, which is critical for constructing the excitation energy transfer pathways and for a deeper understanding of the molecular mechanism of state transitions progress. In this review, we focus on the structural data of the state 2 supercomplex from plants and green algae and discuss the current state of knowledge concerning the interactions between antenna and the PSI core and the potential energy transfer pathways in these supercomplexes. [ABSTRACT FROM AUTHOR]

Abstract The main purpose of this paper is using the elementary method to study the LCM Sequence, and give an asymptotic formula about this sequence. Keywords Smarandache LCM Sequence, limitation. [...]

Abstract Let a be any fixed square free number, the irrational root sieve sequence is defined as taking off all k-powers (k ≥ 2), of all square free numbers a [...]

Let a be a positive integer with $a>1$ , and let $(x, y, n)$ be a positive integer solution of the equation $x^{2}+a^{2}=y^{n}$ , $\gcd(x, y)=1$ , $n>2$ . Using Baker's method, we prove that, for any positive number ϵ, if n is an odd integer with $n>C(\epsilon)$ , where $C(\epsilon)$ is an effectively computable constant depending only on ϵ, then $n<(2+\epsilon)(\log a)/\log y$ . Owing to the obvious fact that every solution $(x, y, n)$ of the equation satisfies $n>2(\log a)/\log y$ , the above upper bound is optimal. [ABSTRACT FROM AUTHOR]

Recent structural data revealed thatthe CP29 protein of higher plant photosystem II (PSII) contains 13chlorophylls (Chl’s) per complex (Pan et al. Nat. Struct.Mol. Biol. 2011, 18, 309),i.e., five Chl’s more than in the predicted CP29 homology-basedstructure model (Bassi et al. Proc. Natl. Acad. Sci. U.S.A.1999, 96, 10056). This lack of consensuspresents a constraint on the interpretation of CP29 optical spectraand their underlying electronic structure. To address this problem,we present new low-temperature (5 K) absorption, fluorescence, andhole-burned (HB) spectra for CP29 proteins from spinach, which arecompared with the previously reported data. We focus on excitationenergy transfer (EET) and the nature of the lowest-energy state(s).We argue that CP29 proteins previously studied by HB spectroscopylacked at least one Chl amolecule (i.e., a615 or a611), which along with Chl a612 contribute to the lowest energy state in more intactCP29, and one Chl b(most likely b607). This is why the low-energy state and fluorescence maxima reportedby Pieper et al. (Photochem. Photobiol.2000, 71, 574) were blue-shifted by ∼1 nm, thelow-energy state appeared to be highly localized on a single Chl amolecule, and the position of the low-energy state wasindependent of burning fluence. In contrast, the position of the nonresonantHB spectrum shifts blue with increasing fluence in intact CP29, asthis state is strongly contributed to by several pigments (i.e., a611, a612, a615, and a610). Zero-phonon hole widths obtained for the Chl bband at 638.5 nm (5 K) revealed two independent Chl b→ Chl aEET times, i.e., 4 ±0.5 and 0.4 ± 0.1 ps. The latter value is a factor of 2 fasterthan previously observed by HB spectroscopy and very similar to theone observed by Gradinaru et al. (J. Phys. Chem. B2000, 104, 9330) in pump–probeexperiments. EET time from 650 nm Chl b→Chl aand downward EET from Chl(s) astate(s) at 665 nm occurs in 4.9 ± 0.7 ps. These findings provideimportant constraints for excitonic calculations that are discussedin the accompanying paper (part II, DOI 10.1021/jp4004278). [ABSTRACT FROM AUTHOR]