Ammonium niobium oxalate was prepared and characterized by elemental analysis, XRD and FTIR spectroscopy analysis, which confirmed
that the molecular formula of the complex is NH4(NbO(C2O4)2(H2O)2)(H2O)3. Dynamic TG analysis under air was used to investigate the thermal decomposition process of synthetic ammonium niobium oxalate.
It shows that the thermal decomposition occurs in three stages and the corresponding apparent activation energies were calculated
with the Ozawa–Flynn–Wall and the Friedman methods. The most probable kinetic models of the first two steps decomposition
of the complex have been estimated by Coats–Redfern integral and the Achar–Bridly–Sharp differential methods.
The thermal decompositions of dehydrated or anhydrous bivalent transition metal (Mn, Fe, Co, Ni, Cu, Zn, Cd) and alkali rare
metal (Mg, Ca, Sr, Ba) methanesulfonates were studied by TG/DTG, IR and XRD techniques in dynamic Air at 250–850 °C. The initial
decomposition temperatures were calculated from TG curves for each compound, which show the onsets of mass loss of methanesulfonates
were above 400 °C. For transition metal methanesulfonates, the pyrolysis products at 850 °C were metal oxides. For alkali
rare metal methanesulfonates, the pyrolysis products at 850 °C of Sr and Ba methanesulfonates were sulphates, while those
of Mg and Ca methanesulfonate were mixtures of sulphate and oxide.
Hydrated methanesulfonates Ln(CH3SO3)3nH2O (Ln=La, Ce, Pr, Nd and Yb) and Zn(CH3SO3)2nH2O were synthesized. The effect of atmosphere on thermal decomposition products of these methanesulfonates was investigated.
Thermal decomposition products in air atmosphere of these compounds were characterized by infrared spectrometry, the content
of metallic ion in thermal decomposition products were determined by complexometric titration. The results show that the thermal
decomposition atmosphere has evident effect on decomposition products of hydrated La(III), Pr(III) and Nd(III) methanesulfonates,
and no effect on that of hydrated Ce(III), Yb(III) and Zn(II) methanesulfonates.
Authors:D. Zhou, H. Gong, Z. Luan, J. Hu, and F. Wu
The study site is the Honghe National Nature Reserve, a Ramsar designated site on the Sanjiang Plain in Northeast China. We present results regarding the spatial pattern and structure of plant communities in these most important natural but continually diminishing freshwater wetlands of China to help promote both protection and restoration. By investigating three ecological levels (landscape, ecosystem and community), this paper quantifies the characteristics of spatial pattern with the aim to identify specific ecological correlations with different hydrogeomorphic features. Specifically, the research involves hierarchical mapping of vegetation types by use of remote sensed data, and the coupling of landscape indices with fluvial topographic zones that have been deduced by GIS from DEM. Statistics from historical survey data are also used to measure the degradation of marshes as well as the historical change of the hydrological regime. We found that dominant is the
Calamagrostis angustifolia — Carex
spp. community type, a wet meadow and marsh complex within the prevailing landscape mosaic of shrubland and meadow. The results suggest that the sites’ hydro-geomorphic character has decisive influence on plant community structure and composition. There is only limited direct human interference in the sites and, as a consequence, the spatial pattern of vegetation distribution is natural. However, changes to the hydrological regime as the result of extensive irrigation activity in the surrounding area has led to rapid degradation of marsh wetlands within the sites, which threatens the ecological status in this storehouse of “Natural Genes” in the reserve.
Authors:Y. Feng, S. Zhang, X. Peng, J. Yuan, Y. Yang, H. Zhan, and Y. Gong
In mammals, testis development is initiated by the expression of the sex-determining gene,
, where-as the genetic trigger for sex determination in birds remains unknown. In the present study, the expression of seven genes implicated in vertebrate sex determination and differentiation were studied in chicken embryonic gonads from day 4 to day 12 of incubation using reverse transcription and the polymerase chain reaction (RT-PCR). Results showed transcription of c
were sexually dimorphic during chicken gonadal development, whereas c
were expressed at similar levels in both sexes. Results of comparative studies between mammals and chickens show that vertebrate sex-determining pathways comprise both conserved and divergent elements: expression profiles of c
are similar to those in mammals, while others appear some differences. Possible functions of these genes on chicken gonadal development were analyzed based on their expression profiles.
Iron deficiency is the most common nutritional disorder, affecting over 30% of the world’s human population. The primary method used to alleviate this problem is nutrient biofortification of crops so as to improve the iron content and its availability in food sources. The over-expression of ferritin is an effective method to increase iron concentration in transgenic crops. For the research reported herein, sickle alfalfa (Medicago falcata L.) ferritin was transformed into wheat driven by the seed-storage protein glutelin GluB-1 gene promoter. The integration of ferritin into the wheat was assessed by PCR, RT-PCR and Western blotting. The concentration of certain minerals in the transgenic wheat grain was determined by inductively coupled plasma-atomic emission spectrometry, the results showed that grain Fe and Zn concentration of transgenic wheat increased by 73% and 44% compared to nontransformed wheat, respectively. However, grain Cu and Cd concentration of transgenic wheat grain decreased significantly in comparison with non-transformed wheat. The results suggest that the over-expression of sickle alfalfa ferritin, controlled by the seed-storage protein glutelin GluB-1 gene promoter, increases the grain Fe and Zn concentration, but also affects the homeostasis of other minerals in transgenic wheat grain.