Electric dichroism studies on ferriheme– and ferroheme–poly(L-lysine) complexes at pH 9–12

Transient electric dichroism has been measured for the ferriheme–poly(L -lysine)[(Lys)_n], ferroheme–(Lys)_n, and ferroheme–(Lys)_n–carbon monoxide (CO) solutions at pH 9–12. The Soret absorption maximum in electronic spectrum (λ), the reduced linear dichroism (ρ_∞) at complete orientation and the calculated angle (?) between the porphyrin plane of a bound heme and the oriented polymer axis are determined for the following complexes: a ferriheme–(Lys)_n complex at pH 9.5–10.5 (λ = 420 nm, ρ_∞ = 0.50, and ? = 19°), a ferroheme–(Lys)_n complex at pH 9.5–10.2 (λ = 432 nm, ρ_∞ = 0.77, and ? = 0°), and a ferroheme–(Lys)_n–CO complex at pH 9.25 (λ = 430 nm, ρ_∞ = 0.38, and ? = 24°). Based on the above data, the validity of the structures of heme–(Lys)_n complexes proposed by other investigators is discussed.     

Demography of Reintroduced Eastern Bluebirds and Brown-Headed Nuthatches

ABSTRACT Species reintroductions are used commonly as a tool for conservation, but rigorous, quantitative assessments of their outcome rarely occur. Such assessments are critical for determining success of the reintroduction and for identifying management actions needed to ensure persistence of reintroduced populations. We collected 9 years of demographic data on populations of brown-headed nuthatches (Sitta pusilla) and Eastern bluebirds (Sialia sialis) reintroduced via translocation into Long Pine Key, Everglades National Park, Florida, USA. Realized population growth of brown-headed nuthatches was positive in the first 3 years after cessation of translocations (λ₂₀₀₂ = 1.15, SE = 0.13; λ₂₀₀₃ = 1.28, SE = 0.12; λ₂₀₀₅ = 1.32, SE = 0.20) but became negative thereafter (λ₂₀₀₆ = 0.67, SE = 0.10; λ₂₀₀₇ = 0.77, SE = 0.13). Realized growth rate for the Eastern bluebird population did not vary among years and indicated either a stable or a slowly declining population (λ = 0.92, SE = 0.04). Reintroductions were a qualified success; they resulted in the re-establishment of populations of both species, but neither population grew to the extent expected and both remained at risk of extinction.     

Various X2-Tests of Homogeneity: Some Comments

Methodological issues in the analysis of incidence rates or prevalence proportions for count data, presented in a form of a sequence of 2×2 tables, corresponding to levels (strata) of a specified variable (risk factor) X, are discussed. Suppose λ_1i and λ_2i are the incidence rates of an event D in the ith stratum for populations 1 and 2, respectively. The homogeneity (null) hypothesis is formulated in the form: H_0:λ1i=λ_2i for all i (i = 1, 2, …, I). Three X²-tests for H₀ and their theoretical bases are discussed: X_Total² which is sensitive to alternatives HA :λ1i± λ2i for at least some i; X_Comb² which is sensitive to alternatives H A : λ1iλ2i² or < λ_2i but not both for all i; and X_Diff² which is sensitive to alternatives H_A:λ1i>λ2i³ for some i and λ_1i′ < λ_2i′ for some i′ (i≠i′). These statistics satisfy the relation X_Total² = X_Comb² + X_Diff². Also, X′²-statistic for pooled data is calculated, which in conjunction with X_Comb² can serve for detecting confounding. Although most of these techniques are known, they are rather scattered in the literature, and not always considered jointly, as it is emphasized in the present paper. It is hoped that these comments will be helpful to biostatisticians as well as to epidemiologists and medical researchers in the analysis of mortality and morbidity data. For illustration, two examples with large sets of epidemiological data are given.     

Limiting laws and counterion condensation in polyelectrolyte solutions: V. Further development of the chemical model

Counterion binding to polyelectrolyte chains is formulated as a chemical reaction M^z(free) → M^z(bound). Expressions for the chemical potentials of free and bound counterions are set equal to obtain the reaction equilibrium. The results are equivalent to those in the previous paper of this series. An additional result obtained here is that a polyion holds its bound counterion layer with a strength on the order of 100 $\text{kcal}\text{(mole cooperative unit)}$. The method is then applied to the calculation of the polarizability along the chain due to the bound (condensed) counterions.     

Diary

Abstract

The formation of sparingly soluble Ca²⁺-phytate (Phy) species was studied using several techniques (potentiometry, calorimetry, thermoanalysis, ICP, SEM). Species with empirical formula Ca_xH(₁₂__2x)Phy, (6 ≤ x ≤ 4.5) were formed in experiments performed at pH = 5.0, 7.5 and 10.5; at pH = 10.5 and in excess of Na+ the species Ca₅Na₂Phy was also found. Solubilities (s = 1.0 x 10^-9and 1.1 x 10^-10mol L^-1 for the species Ca₆Phy and Ca₅Na₂Phy respectively, at l = 0 mol L^-1), thermogravimetric profiles (dehydratation, monohydrogen-phosphate and final pyrophosphate formation), and formation enthalpies (ΔΗ = 7.6 ± 1 and 3.7 ± 0.8 kJ mol^-1for the equilibria 6Ca²⁺ + H₃L^9- = Ca₆L⁰ + 3 H⁺ and 5Ca²⁺ + 2Na⁺ + H₃L^9- = Ca₅Na₂L⁰ + 3 H⁺, respectively), were obtained.     

Investigation on the co‐luminescence effect of europium (III)–lanthanum(III)–dopamine–sodium dodecylbenzene sulfonate system and its application

A novel luminescence, enhancement phenomenon in the europium(III)–dopamine–sodium dodecylbenzene sulfonate system was observed when lanthanum(III) was added. Based on this, a sensitive co‐luminescence method was established for the determination of dopamine. The luminescence signal for the europium (III)–lanthanum(III)–dopamine–sodium dodecylbenzene sulfonate system was monitored at λ_ex = 300 nm, λ_em =618 nm and pH 8.3. Under optimized conditions, the enhanced luminescence signal responded linearly to the concentration of dopamine in the range 1.0 × 10^–10–5.0 × 10^–7 mol/L with a correlation coefficient of 0.9993 (n = 11). The detection limit (3σ) was 2.7 × 10^–11 mol/L and the relative standard deviation for 11 parallel measurements of 3.0 × 10^–8 mol/L dopamine was 1.9%. The presented method was successfully applied for the estimation of dopamine in samples of pharmaceutical preparations, human serum and urine. The possible luminescence enhancement mechanism of the system is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.     

Product inhibition during the feeding phasein fed-batch ethanol fermentation of sugar-cane blackstrap molasses

Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: = ₀ - k · E and v = v ₀ · K/(K +E) Nomenclature E ethanol concentration in the aqueous phase of the fermenting medium (g.L^–1) - E_m value of E when = 0 or = 0 (g.L^–1) - F medium feeding rate (L.h^–1) - k empirical constant (L.g^–1.h^–1) - K empirical constant (g.L^–1) - M_as mass of TRS added to the, reactor (g) - M_cs mass of consumed TRS (g) - M_e mass of ethanol in the aqueous phase of the fermenting medium (g) - M_s mass of TRS in the aqueous phase of the fermenting medium (g) - M_x mass of yeast cells (dry matter) in the fermenting medium (g) - r correlation coefficient - S TRS concentration in the aqueous phase of the fermenting medium (g.L^–1) - S_m TRS concentration of the feeding medium (g.L^–1) - t time (h) - T temperature (° C) - TRS total reducing sugars calculated as glucose - V volume of the fermenting medium (L) - V₀ volume of the inoculum (L) - X yeast cells concentration (dry matter) in the fermenting medium (g.L^–1) - filling-up time (h) - specific growth rate of the yeast cells (h^–1) - ₀ value of when E=0 - specific production rate of ethanol (h^–1) - ₀ value of when E=0 - density of the yeast cells (g.L^–1) - dry matter content of the yeast cells     

Trivalent counterion condensation on DNA measured by pulse gel electrophoresis

Pulse gel electrophoresis was used to measure the reduction of mobilities of λ-DNA-Hind III fragments ranging from 23.130 to 2.027 kilobase pairs in Tris borate buffer solutions mixed with either hexammine cobalt(III), or spermidine³⁺ trivalent counterions that competed with Tris⁺ and Na⁺ for binding onto polyion DNA. The normalized titration curves of mobility were well fit by the two-variable counterion condensation theory. The agreement between measured charge fraction neutralized and counterion condensation prediction was good over a relatively wide range of trivalent cation concentrations at several solution conditions (pH, ionic strength). The effect of ionic strength, trivalent cation concentration, counterion structure, and DNA length on the binding were discussed based on the experimental measurements and the counterion condensation theory. © 1996 John Wiley & Sons, Inc.     

Flow injection chemiluminescence determination of acetochlor and cartap-HCl in freshwater samples using an acidic KMnO4–rhodamine-B reaction system

A flow injection (FI) methodology using the acidic potassium permanganate (KMnO₄)–rhodamine-B (Rh-B) reaction with chemiluminescence (CL) detection was established to determine acetochlor and cartap-HCl pesticides in freshwater samples. Experimental parameters were optimized, and Chelex-100 cationic exchanger mini column and solid-phase extraction (SPE) were used as phase separation techniques. Linear calibration curves were observed for the standard solutions of acetochlor and cartap-HCl over the ranges 0.005–2.0 mg L⁻¹ [y = 1155.8x + 57.551, R² = 0.9999 (n = 8)] and 0.005–1.0 mg L⁻¹ [y = 979.76x + 14.491, R² = 0.9998 (n = 8)] with LODs and LOQs of 7.5 × 10⁻⁴ and 8.0 × 10⁻⁴ mg L⁻¹ (3σ blank) and 2.5 × 10⁻³ and 2.7 × 10⁻³ mg L⁻¹ (10σ blank), respectively, with an injection throughput of 140 h⁻¹. These methods were used to estimate acetochlor and cartap-HCl with or without the SPE procedure, respectively, in spiked freshwater samples. Results obtained were not significantly different at a 95% confidence level to those of other reported methods. Recoveries for acetochlor and cartap-HCl were obtained over the ranges 93–112% (RSD = 1.9–3.6%) and 98–109% (RSD = 1.7–3.8%), respectively. The most probable CL reaction mechanism was explored.     

Functional similarities of AeEα Ia molecules as determined by analysis with T-cell clones

Recognition of A_eE Ia antigens at the functional level was investigated using T-cell clones. The reactivities of an alloreactive and an antigen-reactive clone, both of which recognized A_eE Ia molecules, were compared on a panel of stimulator/antigen-presenting cells of various genotypes. The two clones recognized all tested A _e ^b E ^x Ia molecules, where x is a haplotype capable of expressing an Ia.7-bearing E polypeptide. Ia antigen recognition by either clone could be inhibited by the monoclonal antibody Y-17, which recognizes a combinatorial serologic determinant on certain A_eE molecules. There were no differences in the recognition of Ia by the alloreactive versus the antigen-reactive clone, suggesting that Ia antigens are recognized by the two clones in a fundamentally similar way. The recognition of these various Ia molecules by the two cloned T-cell lines provides evidence that the E polypeptides from H-2 haplotypes k, d, r, and u are functionally indistinguishable.Abreviations MHC major histocompatibility complex - Mb myoglobin - MLR mixed leukocyte reaction - PBS phosphate buffered saline - APC antigen presenting cell - KLH keyhole limpet hemocyanin - GAT poly (glut⁶⁰ alai³⁰ tyr¹⁰)n - (TG)-A—L poly (L-tyr, L-glu)-poly (D, L-ala)—poly L-lys - GLPhe poly (glu⁵⁵ lys³⁶ phe⁹)n     

Synthesis, structure, solution chemistry and the electronic effect of para substituents on the vanadium center in a family of mixed-ligand [VO(ONO)(ON)] complexes

Four tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoylhydrazine with either 2-hydroxyacetophenone or its para substituted derivatives (H₂L^1-4, general abbreviation H₂L) have been used as primary ligands and 8-hydroxyquinoline (Hhq, a bidentate monobasic ON donor species) has been used as auxiliary ligand. The reaction of [V^IVO(acac)₂] with H₂L in methanol followed by the addition of Hhq in equimolar ratio under aerobic condition afforded the mixed-ligand oxovanadium(V) complexes of the type [V^VO(L)(hq)] (1-4) in excellent yield. The X-ray structure of the compound [V^VO(L⁴)(hq)] (4) indicates that the H₂L⁴ ligand is bonded with vanadium meridionally in a tridentate dinegative fashion through its deprotonated phenolic-O, deprotonated enolic-O and imine-N atoms. The V-O bond length order is: oxo < phenolato < enolato. ¹H NMR spectra of 4 in CDCl₃ solution indicates that it’s solid-state structure is retained in solution. Complexes are diamagnetic and exhibit only ligand to metal charge transfer (LMCT) transition band near 530 nm in CH₂Cl₂ solution in addition to intra-ligand π → π^∗ transition band near 335 nm and they display quasi-reversible one electron reduction peak near − 0.10 V versus SCE in CH₂Cl₂ solution. λ_max (for LMCT transition) and the reduction peak potential values of the complexes are found to be linearly related with the Hammett (σ) constants of the substituents in the aryloxy ring of the hydrazone ligands. λ_max and values show large dependence dλ_max/dσ = 32.54 nm and V, respectively, on the Hammett constant.     

Generalized Bohm’s criterion and negative anode voltage fall in electric discharges

The value of the voltage fall across the anode sheath is found as a function of the current density. Analytic solutions are obtained in a wide range of the ratio of the directed velocity of plasma electrons v ₀ to their thermal velocity v _T . It is shown that the voltage fall in a one-dimensional collisionless anode sheath is always negative. At the small values of v ₀/v _T , the obtained expression asymptotically transforms into the Langmuir formula. Generalized Bohm’s criterion for an electric discharge with allowance for the space charge density ρ(0), electric field E(0), ion velocity v _i (0), and ratio v ₀/v _T at the plasma-sheath interface is formulated. It is shown that the minimum value of the ion velocity v _i ^* (0) corresponds to the vanishing of the electric field at one point inside the sheath. The dependence of v _i ^* (0) on ρ(0), E(0), and v ₀/v _T determines the boundary of the existence domain of stationary solutions in the sheath. Using this criterion, the maximum possible degree of contraction of the electron current at the anode is determined for a short high-current vacuum arc discharge.     

Photoluminescence properties of LiTi2 − xEux(PO4)3 phosphor

A solid‐state reaction route‐based LiTi_{2 ? x}Eu_x(PO₄)₃ was phosphor synthesized for the first time to evaluate its luminescence performance by excitation, emission and lifetime (τ) measurements. The LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor was excited at λ_exci. = 397 nm to give an intense orange–red (597 nm) emission attributed to the ⁵D₀ → ⁷F₁ magnetic dipole (ΔJ = ±1) transition and red (616 nm) emission (⁵D₀ → ⁷F₂), which is an electric dipole (ΔJ = ±2) transition of the Eu³⁺ ion. Beside this, excitation and emission spectra of host LiTi₂(PO₄)₃ powder were also reported. The effect of Eu³⁺ concentration on luminescence characteristics was explained from emission and lifetime profiles. Concentration quenching in the LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor was studied from the Dexter's model. Dipole–quadrupole interaction is found to be responsible for energy transfer among Eu³⁺ ions in the host lattice. The LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor displayed a reddish‐orange colour realized from a CIE chromaticity diagram. We therefore suggest that this new phosphor could be used as an optical material of technological importance in the field of display devices. Copyright © 2016 John Wiley & Sons, Ltd.     

Luminescence behavior of Li2Sr1‐3x/2EuxSiO4 red phosphors for LED applications

Red‐emitting Li₂Sr_1‐3x/2Eu_xSiO₄ 0≤x≤0.5) phosphors were synthesized at 900°C in air by a solid‐state reaction. The synthesized phosphors were characterized by X‐ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the ⁵L₆ state of Eu³⁺ ions is of significance for near ultraviolet pumped white light‐emitting diodes and solid‐state lighting. It is also noted that the position of the charge transfer state of Eu³⁺ ions shifts towards the higher energy side (blue shift) by increasing the content of Eu³⁺ ions. The predominant emissions of Eu³⁺ ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red‐emitting Li₂Sr_1‐3x/2Eu_xSiO₄ phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light‐emitting diode applications. Copyright © 2013 John Wiley & Sons, Ltd.     

F-tests for Hypotheses with Block Matrices and Under Conditions of Orthogonality in the General Multivariate Gauss-Markoff Model

The multivariate general Gauss-Markoff (MGM) model (U, XB, ∑?σ²V) when the matrices V ≥ 0 and ∑ > 0 are known and the scalar σ² > 0 is unknown, is considered. The present paper is a continuation of two earlier works (Oktaba, 1988a, b). If XB = X₁Σ + X₂Δ, then the F-test for verification the hypothesis WΣA = 0 is presented. Moreover, under conditions of orthogonality the decomposition of the matrix S_A (?BCA)′L^?(?BCA) into the sum of s = r(L) matrices is given, where ?BCA is the estimator of the parametric estimable functions ?BCA, Cov (?BCA) = A′ ∑?σ²L = ?C₄?′, B? = (X′T^?X)^?X′T^?U, C₄ = (X′T^?X)^?M, where M = M′ is any arbitrary matrix such that R(X) ? R(T), T=V+XMX′; T^? is any c-inverse. R(A) is the linear space generated by the colums of A. Then under additional assumption on normality of U the statistics F for testing ?BA = 0 is deduced. Under conditions of normality of U and decomposition of S_A, the statistics F₁, …, F_s for the hypotheses jⁱ BA = 0 (i = 1,…, s) are established.     

Evapotranspiration by Eichhornia crassipes (Mart.) Solms and Typha latifolia L.

Evapotranspiration (E) by Eichhornia crassipes (Mart.) Solms and Typha latifolia L. growing in 5.77-m² tanks and evaporation (E₀) from control tanks were measured over a 6-month period at Auburn, Alabama (32.5° N latitude). The E/E₀ ratios for E. crassipes and T. latifolia were 1.31–2.52 (mean = 1.75) and 1.05–2.50 (mean = 1.62), respectively. Evidence is presented which demonstrates that E/E₀ values were similar to those which occur in natural populations of the two species. Both plant characteristics and meteorological variables influenced evapotranspiration. Equations for estimating evapotranspiration were E_Ec = (4.19 + (7.32 × 10⁻⁸) S² + (0.00035 × 10⁻³)H²)D R² = 0.92E_Tl = (1.43 + (2.79 × 10⁻¹⁵)S⁴ + 1.44L)D R² = 0.93 where E_Ec and E_Tl are monthly water loss in mm/month for E. crassipes and T. latifolia, respectively; S is the average daily solar radiation in W m⁻² integrated over 24 h for the month; H is plant height in m; L is leaf area index (dimensionless); and D is the number of days in the month.     

A blue chemiluminescence in the reaction of umbelliferone with hypochlorite

A strongly fluorescing 7-hydroxycoumarin (umbelliferone, U) oxidized in dilute (10 μmol/L-0, 1 mol/L) aqueous solution with CIO^? or CIO^? + H₂O₂ (but not with H₂O₂ alone) produces a strong chemiluminescence (CL). Light emission kinetics depends on the pH of solution (4.0–10.5) and the reaction has a low activation energy E_a = 31 ± 2 kJ/mol (285–310 K). The spectrum covers the fluorescence of umbelliferone (400–550 nm, λ_max 460nm). No red emission typical of ¹Δg, ¹Σ⁺g (O₂)₂ is observed either in the umbelliferone +CIO^? or the umbelliferone +CIO^? + H₂O₂ solution. The possible mechanism of CL and concomitant degradative oxidation of umbelliferone is discussed.     

Dynamics and viability analysis of transplanted and natural lady's slipper (Cypripedium japonicum) populations under habitat management in South Korea

To assess the effectiveness of conservation‐based transplantation of the endangered orchid (Cypripedium japonicum), we compared the morphology, physiology, stem‐count change, and population viability of natural versus transplanted populations undergoing habitat management (repeated removal of competing understory vegetation) between 2009 and 2015 in South Korea. The restored site had lower transmitted light and soil humidity than the natural site. The natural and transplanted populations differed in leaf morphology and total chlorophyll content (natural: 1.00 ± 0.04, restored: 0.53 ± 0.06). No recruitment occurred during the monitoring period. Population viability tended to decrease in the restored population (λ_G = 0.97, μ = ?0.05, σ² = 0.036) and increase in the natural population (λ_G = 1.07, μ = 0.03, σ² = 0.075). The repeated removal of competing understory vegetation had different effects on leaf traits, abundance, and reproductive properties of the endangered orchids in both populations. Notably, habitat management increased the stem count and flowering rate in natural C. japonicum but did not increase the fruit‐setting rate. Thus, despite repeated habitat management efforts (removal of competing understory vegetation), we conclude that the population viability of transplanted populations of the endangered orchid C. japonicum had poor long‐term viability compared with naturally occurring populations, a difference that is mainly attributed to inappropriate transplant‐site selection.