Highly sensitive and accurate profiling of carotenoids by supercritical fluid chromatography coupled with mass spectrometry

We attempted to establish a high‐speed and high‐resolution profiling method for a carotenoid mixture as a highly selective and highly sensitive detection method; the analysis was carried out by supercritical fluid chromatography (SFC) coupled with mass spectrometry (MS). When an octadecyl‐bonded silica (ODS) particle‐packed column was used for separation, seven carotenoids including structural isomers were successfully separated within 15 min. This result indicated not only improved separation but also improved throughput compared to the separation and throughput in RP‐HPLC. The use of a monolithic ODS column resulted in additional improvement in both the resolution and the throughput; the analysis time was reduced to 4 min by increasing the flow rate. Furthermore, carotenoids in biological samples containing the complex matrices were separated effectively by using several monolithic columns whose back pressure was very low. The mass spectrometer allowed us to perform a more sensitive analysis than UV detection; the detection limit of each carotenoid was 50 pg or below. This is the first report of carotenoid analysis carried out by SFC‐MS. The profiling method developed in this study will be a powerful tool for carrying out accurate profiling of biological samples.     

Brönsted acid ionic liquid-catalyzed direct benzylation, allylation and propargylation of 1,3-dicarbonyl compounds with alcohols as well as one-pot synthesis of 4H-chromenes

Recyclable ionic Brönsted acid was prepared in nearly quantitative yield by reacting 1-butylimidazole with an equimolar amount of 1,3-propanesultone, followed by treatment with an equimolar amount of trifluoromethanesulfonic acid. The ionic Brönsted acid-catalyzed direct benzylation, allylation and propargylation of 1,3-dicarbonyl compounds with various alcohols in ionic liquid [N-ethyl-N-methyl imidazolium trifluoromethanesulfonate (EMIOTf)], at 100 °C for 3 h proceeded smoothly to give the corresponding products in good to excellent yields without the use of any hazardous or volatile solvents and without any by-product such as salts. Furthermore, tandem benzylation-cyclization-dehydration of 1,3-dicarbonyl compounds to give functionalized 4H-chromenes was also achieved in this catalytic reaction.     

Chelation of cadmium ions by phytochelatin synthase: role of the cysteine-rich C-terminal.

The interactions between Cd(2+) and the C-terminal region of phytochelatin (PC) synthase using recombinant wild-type and mutant PC synthase were studied. We show that site-directed mutagenesis of Cys residues at C(358)C(359)XXXC(363)XXC(366) motif decreases the number of Cd(2+) and other heavy metal ions interacting with the enzyme, and that the motif binds the metals discriminatingly. The optimum binding ratio of PC synthase to Cd(2+) was also determined. The findings indicate that Cys exists as a free SH residue and that it is involved in the regulation of PC enzyme activity by transferring the metals into closer proximity with the catalytic domain. These results are important in understanding heavy metal detoxification mechanisms in higher plants, a step towards phytoremediated-applications.     

Deracemization of 1,2-diol monotosylate derivatives by a combination of enzymatic hydrolysis with the Mitsunobu inversion using polymer-bound triphenylphosphine

The deracemization of 1,2-diol monotosylate derivatives is achieved by the sequential combination of enzymatic hydrolysis and Mitsunobu inversion using a polymer-bound triphenylphosphine. After the lipase-catalysed hydrolysis of the racemic 2-acetoxyhexyl tosylate, the subsequent Mitsunobu reaction without separation causes an inversion of the resulting (R)-alcohol to give the (S)-enantiomer of the acetate as a single product. In particular, the reaction using the polymer-bound triphenylphosphine also proceeds smoothly, and the product is easily separated by filtration from the polymer-bound reagent and its by-products. This deracemization process is applicable to the preparation of several optically active 1,2-diol monotosylates.     

Distance degree regular graphs

In this note, inequalities between the distance degrees of distance degree regular graphs and to characterize the graphs when one of the equalities holds are proved.     

Determination of Cu, Pb, Fe, and Zn in plant component polymers of a hyperaccumulating plant.

Phytoremediation is an innovative technology that utilizes the natural properties of plants to remediate hazardous waste sites. For more cost-effective phytoremediation, it is important to utilize a hyperaccumulating plant after phytoremediation, i.e. the recovery of valuable metals and the production of useful materials. In this work, the determination of metals in plant component polymers in a fern, Athyrium yokoscense, as a hyper-accumulating plant was established using steam explosion, Wayman's extraction method, and ICP emission spectrometry. After A. yokoscense plants were treated by steam explosion, the steam-exploded A. yokoscense were separated into four plant component polymers, ie. water-soluble material fraction, holocellulose fraction, methanol-soluble lignin fraction, and residual lignin fraction. The concentrations of Cu, Pb, Fe, and Zn in these plant component polymers and the dry weights of plant component polymers were measured. These analytical process determining metals in the plants will contribute to not only the evaluation and the efforts of phytoremediation using a hyperaccumulating plant, but also to the development of more effective phytoremediation.     

Tridiagonal matrices with nonnegative entries

In this paper, we characterize the nonnegative irreducible tridiagonal matrices and their permutations, using certain entries in their primitive idempotents. Our main result is summarized as follows. Let d denote a nonnegative integer. Let A denote a matrix in R and let denote the roots of the characteristic polynomial of A. We say A is multiplicity-free whenever these roots are mutually distinct and contained in R. In this case E_i will denote the primitive idempotent of A associated with theta_i(0?i?d). We say A is symmetrizable whenever there exists an invertible diagonal matrix Δ∈R such that ΔAΔ^-1 is symmetric. Let Γ(A) denote the directed graph with vertex set {0,1,…,d}, where i→j whenever i≠j and A_ij≠0.Theorem.Assume that each entry ofAis nonnegative. Then the following are equivalent for0≤s,t≤d.

(i)

The graphΓ(A)is a bidirected path with endpointss,t:s↔*↔*↔?↔*↔t.

(ii)

The matrixAis symmetrizable and multiplicity-free. Moreover the(s,t)-entry ofE_itimes(θ_i-θ₀)?(θ_i-θ_i-1)(θ_i-θ_i+1)?(θ_i-θ_d)is independent of i for0≤i≤d, and this common value is nonzero.

Recently Kurihara and Nozaki obtained a theorem that characterizes the Q-polynomial property for symmetric association schemes. We view the above result as a linear algebraic generalization of their theorem.     

A classification of sharp tridiagonal pairs

Let F denote a field and let V denote a vector space over F with finite positive dimension. We consider a pair of linear transformations A:V→V and A^∗:V→V that satisfy the following conditions: (i) each of A,A^∗ is diagonalizable; (ii) there exists an ordering of the eigenspaces of A such that A^∗V_i⊆V_i-1+V_i+V_i+1 for 0?i?d, where V_-1=0 and V_d+1=0; (iii) there exists an ordering of the eigenspaces of A^∗ such that for 0?i?δ, where and ; (iv) there is no subspace W of V such that AW⊆W, A^∗W⊆W, W≠0, W≠V. We call such a pair a tridiagonal pair on V. It is known that d=δ and for 0?i?d the dimensions of coincide. The pair A,A^∗ is called sharp whenever . It is known that if F is algebraically closed then A,A^∗ is sharp. In this paper we classify up to isomorphism the sharp tridiagonal pairs. As a corollary, we classify up to isomorphism the tridiagonal pairs over an algebraically closed field. We obtain these classifications by proving the μ-conjecture.     

Growth of undoped and Zn-doped GaN nanowires

Undoped and Zn-doped GaN nanowires were synthesized by chemical vapor deposition (CVD), and the effects of substrates, catalysts and precursors were studied. A high density of GaN nanowires was obtained. The diameter of GaN nanowires ranged from 20 nm to several hundreds of nm, and their length was about several tens of μm. The growth mechanism of GaN nanowires was discussed using a vapor–liquid–solid (VLS) model. Furthermore, room-temperature cathodoluminescence spectra of undoped and Zn-doped GaN nanowires showed emission peaks at 364 and 420 nm, respectively.     

Distribution patterns of gamma radiation dose rate in the high background radiation area of Odisha,India

Journal of Radioanalytical and Nuclear Chemistry - Absorbed dose rates in air for 20 residential areas in Odisha were measured using a vehicle-mounted NaI(Tl) scintillation spectrometer. The...