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Abstract  

Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C. Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that the complexation of Np(V) with sulfate is entropy-driven.

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Abstract  

Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry and microcalorimetry. Two successive complexes, NpO2F(aq) and NpO2F2 , were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase in the stability constants of NpO2F(aq) and more than five-fold increase in the stability constants of NpO2F2 as the temperature is increased from 10 to 70°C.

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Chlorophyll content is positively correlated with photosynthetic rate. However, little is known about the genetic correlation between grain yield and chlorophyll content in the same wheat mapping population. The primary goal of the study was to detect the genetic basis of grain yield and chlorophyll content and their possible roles in the genetic improvement of grain yield in wheat. Here, quantitative trait loci (QTLs) for grain yield and chlorophyll content were studied using a set of 168 doubled haploid (DH) lines derived from a cross between two elite Chinese wheat cultivars, Huapei 3×Yumai 57. The DH population and parents were evaluated for grain yield and chlorophyll content in three environments. A total of 11 additive QTLs and 6 pairs of epistatic QTLs were detected for grain yield and chlorophyll content. Loci, such as Xcfd53, Xwmc718 , and Xwmc215 on chromosomes (e.g. 2D, 4A, and 5D) simultaneously controling grain yield and chlorophyll content, showed tight linkages or pleiotropisms. Three novel major QTLs, qGY5D, qChla5D , and qChlb5D , closely linked with the PCR marker Xwmc215 on chromosome 5D, accounted for 10.32%, 12.95%, and 23.29% of the phenotypic variance, respectively. The favorable alleles came from Yumai 57.

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Abstract  

The stability of β-cyclodextrinethyl benzoate6H2O(β-CDC6H5COOC2H56H2O) was investigated by TG and DSC. The mass loss takes place in three stages: the dehydration occurs at 50-120C; the dissociation of β-CDC6H5COOC2H5occurs at 200-260C; the decomposition of β-CD begins at 280C. The kinetics of the dissociation of β-CDC6H5COOC2H5in a dry nitrogen flow was studied by means of thermogravimetry both at constant temperature and linearly increasing temperature. The results show that the dissociation of β-CDC6H5COOC2H5is dominated by a three-dimensional diffusion process (D3). The activation energy E is 116.19 kJ mol-1and the pre-exponential factor A 6.5358109min-1. Cyclodextrin is able to form inclusion complexes with a great variety of guest molecules, and the studies focus on the energy of binding between cyclodextrin and the guest molecule. In this paper, the β-cyclodextrinethyl benzoate inclusion complex was studied by fluorescence spectrophotometry and infrared absorption spectroscopy, and the results show that the stable energy of inclusion complexes of β-CD with weakly polar guest molecules consists mainly of van der Waals interaction.

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Abstract  

The inclusion complex of benzaldehyde (BA) with β-cyclodextrin (β-CD) was prepared and was studied by thermal analysis and X-ray diffractometry. The composition of the complex was identified by TG and elemental analysis as β-CDBA9H2O. TG and DSC studies showed that the thermal dissociation of β-CDBA9H2O took place in three stages: dehydration in the range 70-120C; dissociation of β-CDBA in the range 235-270C; and decomposition of β-CD above 280C. The kinetics of dissociation of β-CDBA in flowing dry nitrogen was studied by means of TG both at constant temperature and at linearly increasing temperature. The results showed that the dissociation of β-CDBA was dominated by a one-dimensional random nucleation and subsequent growth process (A2). The activation energy E was 124. 8 kJ mol-1, and the pre-exponential factor A 5.041011 min-1.

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Abstract  

On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.

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Abstract  

Analytical quality assurance procedures adopted for use in the IAEA Co-ordinated Research Project on Ingestion and Organ Content of Trace Elements of Importance in Radiological Protection are designed to ensure comparability of the analytical results for Cs, I, Sr, Th, U and other elements in human tissues and diets collected and analysed in nine participating countries. The main analytical techniques are NAA and ICP-MS. For sample preparation, all participants are using identical food blenders which have been centrally supplied after testing for contamination. For quality control of the analyses, six NIST SRMs covering a range of matrices with certified and reference values for the elements of interest have been distributed. A new Japanese reference diet material has also been developed. These quality assurance procedures are summarized here and new data are presented for Cs, I, Sr, Th and U in the NIST SRMs.

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This study aimed to clarify the genetic mechanisms behind wheat flour color. Flour colorrelated traits (L*, a*, and b*) and polyphenol oxidase (PPO) activity are important parameters that influence the end-use quality of wheat. Dissecting the genetic bases and exploring important chromosomal loci of these traits are extremely important for improving wheat quality. The diverse panel of 205 elite wheat varieties (lines) was genotyped using a highdensity Illumina iSelect 90K single-nucleotide polymorphisms (SNPs) assay to disclose the genetic mechanism of flour color-related traits and PPO activity. In 2 different environments and their mean values (MV), 28, 30, 24, and 12 marker-trait associations (MTAs) were identified for L*, a*, b* traits, and PPO activity, respectively. A single locus could explain from 5.52% to 20.01% of the phenotypic variation for all analyzed traits. Among them, 5 highly significant SNPs (P ≤ 0.0001), 11 stable SNPs (detected in all environments) and 25 multitrait MTAs were identified. Especially, BS00000020_51 showed pleiotropic effects on L*, a*, and b*, and was detected in all environments with the highest phenotypic contribution rates. Furthermore, this SNP was also found to be co-associated with wheat grain hardness, ash content, and pasting temperature of starch in previous studies. The identification of these significantly associated SNPs is helpful in revealing the genetic mechanisms of wheat colorrelated traits, and also provides a reference for follow-up molecular marker-assisted selection in wheat breeding.

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Journal of Thermal Analysis and Calorimetry
Authors:
J. Yao
,
F. Wang
,
L. Tian
,
Y. Zhou
,
H. Chen
,
K. Chen
,
N. Gai
,
R. Zhuang
,
T. Maskow
,
B. Ceccanti
, and
G. Zaray

Abstract  

Using TAM III multi-channel calorimetry combined with direct microorganism counting (bacteria, actinomycetes and fungi) under laboratory conditions, we determined the microbial population count, resistance and activity toward cadmium (Cd(II)) and hexavalent chromium (Cr(VI)) toxicity in soil. The thermokinetic parameters, which can represent soil microbial activity, were calculated from power-time curves of soil microbial activity obtained by microcalorimetric measurement. Simultaneous application of the two methods showed that growth rate constant (k), peak-heat output power (P max) and the number of living microorganisms decreased with increasing concentration of Cd and Cr. The accumulation of Cr on E. coli was conducted by HPLC-ICP-MS. Cr6+ accumulation by Escherichia coli was increased steadily with increasing Cr6+ concentration. The results revealed that the change in some thermo-kinetic parameters could have good corresponding relationship with metal accumulation. Our work also suggests that microcalorimetry is a fast, simple, more sensitive, on-line and in vitro method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods, and can combine with other analytic methods to study the interaction mechanism between environmental toxicants and microbes.

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Abstract  

Molar heat capacities (C p,m) of aspirin were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 383 K. No phase transition was observed in this temperature region. The polynomial function of C p,m vs. T was established in the light of the low-temperature heat capacity measurements and least square fitting method. The corresponding function is as follows: for 78 K≤T≤383 K, C p,m/J mol-1 K-1=19.086X 4+15.951X 3-5.2548X 2+90.192X+176.65, [X=(T-230.50/152.5)]. The thermodynamic functions on the base of the reference temperature of 298.15 K, {ΔH TH 298.15} and {S T-S 298.15}, were derived. Combustion energy of aspirin (Δc U m) was determined by static bomb combustion calorimeter. Enthalpy of combustion (Δc H o m) and enthalpy of formation (Δf H o m) were derived through Δc U m as - (3945.262.63) kJ mol-1 and - (736.411.30) kJ mol-1, respectively.

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